OKPAKO BELIEVE, A.

PG/M.ED/07/43174

THE EFFECT OF FEEDING TIME ON THE PERFORMANCE

OF JUVENILE AFRICAN CATFISH (Clarias gariepinus, Burchell 1822)

Faculty of Agriculture

Department of Animal Sciences

Nwamarah Uche

Digitally Signed by: Content manager’s Name

DN : CN = Weabmaster’s name

O= University of Nigeria, Nsukka

OU = Innovation Centre

2

THE EFFECT OF FEEDING TIME ON THE PERFORMANCE

OF JUVENILE AFRICAN CATFISH (Clarias gariepinus, Burchell 1822)

BY

OKPAKO BELIEVE, A.

PG/M.Sc/07/43174

SUPERVIOR: DR. A. O. ANI

UNIVERSITY OF NIGERIA, NSUKKA

DEPARTMENT OF ANIMAL SCIENCE

APRIL, 2010.

i

THE EFFECT OF FEEDING TIME ON THE PERFORMANCE

OF JUVENILE AFRICAN CATFISH (Clarias gariepinus, Burchell 1822)

BY

OKPAKO BELIEVE, A.

PG/M.Sc/07/43174

A THESIS SUBMITTED TO THE DEPARTMENT OF ANIMAL

SCIENCE, FACULTY OF AGRICULTURE IN THE FULFILLMENT OF

THE REQUIREMENT FOR THE AWARD OF MASTER OF SCIENCE

DEGREE UNIVERSITY OF NIGERIA, NSUKKA.

SUPERVIOR: DR. A. O. ANI

APRIL, 2010.

ii

CERTIFICATION

This is to certify that the work embodied in this thesis for the degree of

Master of Science degree of the University of Nigeria, Nsukka was carried out

by Mr. Okpako Believe Ajumiyeri in the Fisheries Unit of the Teaching and

Research Farm of the Department of Animal Science of this University. This

work presented here is original and has not been submitted in part or full for any

other degree of this and any other University

-------------------------- ---------------------------

Dr. A.O. Ani Dr. S.O.C. Ugwu (Project Supervisor) (Head of department)

----------------------------------

External Examiner

iii

DEDICATION

This work is dedicated to my beloved wife Mrs. Okpako, E.O. for all that

she is to me. I truly love her and to our beloved children.

iv

ACKNOWLEDGEMENT

I give all the glory to God who has not only showed Himself as Jehovah

God to me but as a Father. I bow in full reverence unto Him. I immensely

acknowledge all the effort of my supervisor, Dr. A.O. Ani in making sure that

this project becomes a success. No man can reward such an unquantifiable

effort. I sincerely pray that God in His own mercy will do for him what he and

any other mortal cannot do for him in all areas of life. My sincere gratitude goes

to all the staff of the Department of Animal Science who contributed in one way

or the other to the success of this project.

I appreciate my beloved and dearest wife for being there for me

throughout the period of this program. The good God that sees in secret will

reward her openly. I also appreciate our parents for their counsel and prayers. I

cannot forget my Pastors: Rev. W.G. Umukoro and Pastor Dr. Jovi Loyalty for

all the spiritual guidance I received from them. My thanks also go to my

brothers and friends; Deacon Chukwuyenum Emmanuel and Deacon Egbago

Mike for all their supports. My colleagues in the department are worthy of note

especially Mr. Gajah Omawumi. I thank all of them for their numerous

supports.

v

ABSTRACT

The experiment was conducted to investigate the effect of feeding time on the

performance of juvenile African catfish (Clarias gariepinus, Burchell 1822).

The experimental fish were randomly assigned to four treatment groups

(different feeding time intervals) of 60 fish each in a completely randomized

design (CRD). Each treatment was replicated three times with 20 fish per

replicate. The fish were fed with extruded fish feeds (Catco® fish concentrate)

at 3% of the fish body weight. The four treatments (feeding time) were T1 -

once a day feeding time of morning hours (07.30 to 08.30) only, T2- once a day

feeding time of afternoon hours (12.30 to 13.30) only, T3- once a day feeding

time of evening hours (17.00 to 18.00) only and T4- twice a day feeding time of

morning hours (07.30 to 08.30) and evening hours (17.00 to 18.00) only for

twelve weeks. There were significant difference (P<0.05) among treatments in

fish’ final body weight (223.63g, 200.13g, 196.33g and 168.17g for T4, T1, T3

and T2, respectively), mean total body weight gain (208.97g, 184.83, 181.07g

and 153.41g for T4, T1, T3 and T2 ,respectively), mean daily body weight

gain (2.60g, 2.20g 2.16g and 1.83g for T4, T1, T3 and T2, respectively),

specific growth rate (SGR) of 1.41,1.33, 1.32 and 1.26 for T4, T1, T3 and T2,

respectively) and daily feed intake (3.27g, 3.09, 2.95g and 2.54g for T4, T1, T3

and T2, respectively). There were also significant differences (P<0.05) among

treatments in water temperature (26.13 o

C, 25.50oC, 26.43

oC and 28.10

oC for

T4, T1, T3 and T2, respectively). However, there were no significant

differences (P>0.05) among treatments in dissolved oxygen (7.1 mg/l, 6.8mg/l,

7.3 mg/l and 7.5 mg/l for T1, T2, T3 and T4, respectively), water pH (7.1), feed

cost per kg weight gain (N390.00, N380.00, N379.00 and N368.00, for T1, T2,

T3 and T4, respectively) and mortality rate of fish (13.38%, 11.67%, 10.00%

and13.3% for T1, T2, T3 and T4, respectively). It is evident from the result

vi

obtained in the present day study that the growth performance of African catfish

(Clarias gariepinus, Burchell 1822) fed twice a day (in the morning and

evening hours) was superior to the performance of those fed once a day

especially those fed in the afternoon hours only.

vii

TABLE OF CONTENTS

Title page i

Certification ii

Dedication iii

Acknowledgement iv

Abstract v

Table of contents vii

List of Tables ix

List of Figures x

CHAPTER ONE: INTRODUCTION

1.1 Statement of Problem 2

1.2 Aims and Objectives of Study 2

1.3 Justification 3

CHAPTER TWO: LITERATURE REVIEW

2.1 Importance of Fish Farming In Nigeria 4

2.2 Description and Classification of the experimental fish 4

2.3 Feeding Behaviour of Catfish 6

2.3.1 Environmental Feeding Factors 7

2.3.2 Fish Physiological Factors 8

2.3.3 Feeds Factors 10

2.4 Fish Feeding Practice 11

2.4.1 Forms of Fish Feeds and Feeding Stuffs 11

2.4.2 Fish Nutritional Requirements 12

2.4.3 Fish Feeding Rates 14

2.4.4 Feeding Regime 15

viii

2.5 Stocking Rate 16

2.6 Pond Water Quality Management 17

2.6.1 Physical Factors of Pond Water Quality 18

2.6.2 Chemical Factors of Pond Water Quality 21

CHAPTER THREE: MATERIALS AND METHODS

3.1 Location 32

3.2 Materials 32

3.3 Management of the Experimental fish 33

3.4 Experimental Procedures 34

3.5 Parameters measured during the Experiment 34

3.6 Experimental Design 35

3.7 Calculations 35

CHAPTER FOUR: RESULTS AND DISCUSSION

4.1 Growth Performance of African catfish fed at different time

Intervals 36

4.2 Body length of African catfish fed at different time intervals 37

4.3 Physico-chemical characteristic of treatments ponds 37

4.4 Cost implication of feeding African catfish at different time intervals 41

CHAPTER FIVE: SUMMARY AND CONCLUSION

5.1 Summary 42

5.2 Conclusion 43

5.3 Recommendations 43

REFERENCES 44

ix

LIST OF TABLES

Table 1: Nutritional Composition of the Experimental Diet 32

Table 2: Growth Performance of African catfish fed at different 39

time intervals

Table 3: Body Length of African catfish Fed at Different Time Intervals 40

Table 4: Water Temperature, Dissolved Oxygen and pH at Different 40

Time Intervals

Table 5: Cost Implication of Feeding the Fish at Different Time 40

Intervals

x

LIST OF FIGURES

Fig 1: Pictorial View of the African catfish (Clarias gariepinus, Burchell 1822) 6

1

CHAPTER ONE

INTRODUCTION

Aquaculture, the farming of aquatic organisms including fish, molluscs,

crustacean and aquatic plant is necessary to meet the protein need of Nigerians.

Over time, there has been increase in fish production in Nigeria. Bello (2007)

and FAO (2005) reported increase in fish production in 2005. According to him,

the artisan fish production level grew by 5.4%, aquaculture fish production by

43% and industrial fishery through the use trawlers by 12% over the previous

years. However, of this increase in fish production, the desired result has not

been attained. Quantitatively, details of fish production as at 2005 stood at

490,600 tonnes from the artisan fishery, 56,300 tonnes from industrial fishery

through the use of trawlers; while fish importation stood at 61,150 tonnes. In

meeting up with the growing need for fish production, aquaculture practice has

been identified as a possible alternative. The reasons being that the activities of

artisans and industrial fishery in our natural waters have led to over exploitation

and degradation due to human activities in our coastal water. To fully bring

aquaculture to its desired level, four production challenges have been identified.

These are the challenges of feeding the fish stock in the pond, management of

pond water quality, fish seeds provision and pond construction/establishment.

The first two challenges: fish feeding and water quality management affect each

other. The level of feeding of the stocks affects the water quality and the level

of water quality affect the feeding performance of fish in the pond (George,

2001). Fish like other animals need food to be able to carry out their metabolic

activities. In aquaculture, fish feeding is either supplemental or complete (total

supply). Supplemental feeding is when feeds are given to the animal at a

minimal level to add to the natural food available for the fish in the pond water.

These natural foods are in the form of phytoplanktons and zooplanktons. The

complete feeding is when the source of food fed to the fish is solely supplied by

the farmer. In whichever case, the type of feeding practiced depends on the

2

nature of the pond and the type of production the farmer is involved with

(Michael, 1987). The most popular cultured fish in Nigeria is the catfish. It is

naturally carnivorous, a bottom pond dweller, nocturnally very active and

belongs the family of Claridae (William, 1967; Idodo-Umeh, 2003). However,

with the fish domestication, its modes of feeding and activities have been

destabilized and modified. To this end, the feeding regime has become diverse

but the thumb rule of feeding stock at optimum level should be very economical

so as to have savings in feed cost and the overall economic justification.

Webster et al. (1992) reported that catfish can be fed once or twice daily and

rainbow trout at three times a day. In whichever case, the type of production,

climatic condition and economic status of the farmer dictate the feeding

requirement

1.1 Statement of the Problem

According to Raven and Walker (1978), a major problem facing fish feed

manufacturers and fish nutrition is the increasing competition for the same

feeding stuff between man and the fish feed industry due to their conventional

status. This has brought about the high price and scarcity of such feed stuffs.

Various studies have been done in fish feeding (Sena S. De Silva and Brain F.

Davy, 1992 and Collins and Delmendo, 1979) but much is still to be done in the

area of the best time of the day to feed catfish so as to have good growth

performance that will justify the high cost of feeds provided by the farmer. This

will help to forestall the problem of feed wastage and water deterioration (Norm

Meck, 2000).

1.2 Aims and Objectives

1. To determine the growth response of juvenile catfish fed at different time

intervals of the day.

3

2. To determine the best time of the day to feed the African catfish for optimal

performance.

3. To determine the effect of feeding the African catfish at different time

interval of day on fish mortality.

4. To determine the effect of time of feeding the catfish on some physico-

chemical properties of the pond water.

5. To determine the cost implication of feeding juvenile catfish at different time

intervals of the day.

1.3 Justification

It is a known fact that the cost of feeding fish is very high through the

adopted options such as using self formulated feeds or commercial feeds,

supplemental feeding or complete (total) feeding. Determining the best time of

the day to feed the catfish will therefore help to maximize performance,

discourage waste and ensure the success of the enterprise. This will help to

discourage the deterioration of water quality which may arise from the

decomposition of feeds fed to the fish due to feeding at inappropriate time. This

will help to minimize fish mortality due to pond water quality deterioration. The

overall production of the stock will also be enhanced.

4

CHAPTER TWO

LITERATURE REVIEW

2.1 Importance of Fish Farming in Nigeria

Fish farming is fast becoming the bail out point of the protein need of

Africans and Nigerians in particular. Thomas et al. (2006) and Edwin et al.

(2009) posited that fish is the highest contributor of animal protein in Nigeria

with over 34% of all the animal protein sources in Nigeria. This accounts for the

leading position of Nigeria in fish production in Africa from 1999 to date both

in volume and value. In this scenario, the production ecology has it that fish

production from brackish water is about 0.60%, fresh water 72.3% and marine

water 27.1%. Of all these production level, catfish (Clarias spp) ranks the

highest of the cultured fish in Nigeria with about 33%, Oreochromis species

13%, Channa species 4%, Heterotis species 4%, Synodontis species 3%,

Cyprinids 1% and others in the likes of Gymnachus niloticus, Citherinus

species,Hepsetus odeo and Papychranus afer recording about 22%. As a result

of this level of production, Nigeria ranks top in Africa in the use of aqua feed

both of local and exotic sources (Shipton and Thomas, 2005). With this current

status of production in Nigeria, fish farming is still being faced with four major

challenges. These are the challenges of pond construction and other water

holding vessels, feeding and nutrition, quality and volume of fish seeds and

water quality management.

2.2 Description and Classification of the Experimental fish

The African catfish (Clarias gariepinus Burchell, 1822) locally referred

to as mudfish belongs to the Phylum Chordata; Class Osteichytes; Order

Siluriformes; Family Clariidae and Genus Clarias. In Africa, more than one

hundred different species (100) have been identified for which about nine

species features prominently in African aquatic ecology. These are the Clarias

5

gariepinus, Clarias anguillaris, Clarias pachynema, Clarias macromystax,

Clarias agbonyiensis, Clarias buthupogon, Clarias lazera, Clarias

macracanthus and Clarias tsanensis (Graaf et al. 1995 and Idodo-Umeh, 2003).

Mophologically, the Clarias gariepinus is a scale less fish with smooth

skin and soft ray fin, dorsal-ventrally flattened bony head and elongated body

(Yinka et al. 2005 and Idodo-Umeh, 2003) Its dorsal fin has about 61-80 rays

and anal fin of 50 -65 rays. Its head is between rectangular and pointed dorsal

outline with broad snout. It is often described as depressed and long body

shaped fish. The eyes are positioned in the flat depressed head and are relatively

small in size. The depth of its body is 6-8 times its standard length. Its teeth are

vomerine, granular, fine, and are arranged in rows. These common species of

Clarias possess characteristically elongated four pairs of barbells like the cat

whiskers which are 20-50% as long as the head when the fish is longer than

30cm and 50-80% of the head when the length is smaller in size. The Clarias

gariepinus has a number of gill rakers which are long, slender and closely fitted

of about 24 -110 in numbers that increases as the fish grows. The fish has short

dorsal fins that extend as far as to the caudal fin. The pectoral fin extends from

the operculum to below the dorsal fin ray. Its lateral line is swap with white

colouration extending from the posterior end to the middle of the caudal fin

base. The fish has two characteristic colour of dark grey greenish black colour

at the dorsal part while the ventral part is predominantly white. In some

modification, some of them shows band of pigmentation on both side and

irregular black sports (William, 1967; Idodo-Umeh, 2003).

Ecologically, Idodo-Umeh (2003) confirmed that the Clariidae can be

found in stagnant water, lake, pool, and running water body. They are hardy

such that they can survive wide range of extreme aquatic conditions. This

distinct characteristic is traced to their accessory breathing lungs that

compliment their gills which enable them to live several hours outside water

body. The fish is very active at night, a bottom feeder and omnivorous in its

6

feeding pattern. However, they also exhibit predatory behaviour mostly at night

hence they are mostly referred to as nocturnal fish and do not reproduce in

captivity. Naturally therefore, they are involved in migratory breeding during

the onset of rains where they move from deep water to shallow water especially

with running water. In captivity in pond, they often wriggle out of the body of

water to carry out land excursion for a long distance.

Fig 1: Pictorial view of the African catfish (Clarias gariepinus, Burchell 1822)

2.3 Feeding Behaviour of Catfish

Feeding is a complex behaviour of animals including fish. In fish, it

involves several responses associated with eating including modes of feeding

and feeding habits, mechanism of feed detection, frequency of feeding and

preferences of feed provided or found. Fish feeding behaviour ranges from

plant and detritus feeders to predatory feeding. Some fishes based on their

feeding behaviour have become dormant feeders by the fact that they remain in

one spot and source of feeds. Others are sub-dormant feeders which generally

could move away from spot or source of feed or aggressive areas and some are

also sub- ordinate feeders in behaviour. These can stay out of feeding spot or

7

source and still survive on whatever feed items that pass their way (Sunil,

1999). In addition, Colgan (1993) classified some fish as “generalists” feeders,

highly specialized feeders and opportunistic feeders. It also added that hunger

is one great factor that stimulate fish feeding behaviour and that feeding

initially occur at a faster rate in starved fish and degreases as feeding increases.

This is thus in support of restriction feeding and skip a -day feeding practice.

Sorum et al. (2003) informed us that aggression is one feeding behaviour that

could be fixed owe to threat display and fight and every fish has it’s owe life

strategy. These different characteristics response to fish feeding behaviour are

due to three factors that have been identified as factors that affect feeding

behaviour of fish. These are the environmental factors, fish physiological

factors and the feeds factors.

2.3.1 Environmental Feeding Factors

Helene and Richard (2006) identified this factor to be the pond or vessel

water physico-chemical factors such as water temperature, pH, salinity,

dissolved oxygen, environmental photoperiod and the structure of the habitat

like presence of predators, nature of the habitat ( natural or captivity) and the

stock density of the habitat. NRC (2009) reported the influence of water

temperature on the feed intake of Rainbow trout (Salmon gairdneri) where feed

intake increased with increase in temperature from 5oC to 20

oC while below

5oC, feeding activities was low. Yeamin et al. (2007) and Boyd (1982) reported

that in the tropics cultured fish will feed well within the water temperature range

of 26oC and 31.97

oC. In a similar vein, Biswas and Takeuchi (2003) reported

the influence of photoperiod and temperature on tilapia feeding habit. Feeding

will be higher at longer day than at shorter day when temperature is at optimal

level. NRC (2009) confirmed that various fish species respond to different water

salinity level. Feeding activities of the Rainbow trout is highest at 15 to 25%

level of salinity but for fresh water fishes, the higher the salinity the lower the

8

feed intake. It also added that oxygen concentration in water affects feed in take

of fish. When dissolved oxygen in water is high, feeding activities will be

higher and vice versa. Cruz et al.(2000) and Davies et al.(2006) opined that

dissolved oxygen lower than 2mg/l and the water pH range of 5-8 are ideal for

normal feed intake of fish when all other factors are at optimum level. These

water parameters dictate the stress behaviour of fish and their subsequent

reaction. Dissolved oxygen in water will be higher if the ammonia level is low

and the major source of ammonia in pond water is from fish feeding practice

and fish faecal droppings. On the influence of fish habitat of feeding, Paspatis et

al. (2003) indicated that feeding activities of fish will be lower when predators

are present and that social interaction plays another prominent role when fish

are fed in captivity such as pond environment. Fish seems to feed better when

they are fed in group even when the feeds are limited than when alone and the

feed is much. They also reported that proximity to sources or location of feeds

has a marked impact on feed intake. Feeding is highest when feeding spot is

nearer that when far.

2.3.2 Fish Physiological Factors

Various fish physiological states have been identified to affect feeding

behaviour and intake of fish. These physiological factors are in the area of fish

neuro-endocrinological factors and they include stimulations in the fish,

hormonal activities and the different physiological state of the fish. Reporting

the effect of stimulation in the feeding behaviour of fish, Kasumyan (1995) said

that fish exhibits chemosensory behaviour through tactile (touch), gustatory

(taste), olfactory (smell), visual (sight) and auditory (hearing) stimulations as in

other farm animals. These various stimulations are hormonally driven and that

Rainbow trout can even discriminate between diet with fish oil and vegetable

oil. Specifically, the endocrines and the metabolic activities of the fish function

in the characteristic behaviour of feeding. Higgs et al. (1982) reported the

9

cessation of feeding by a number of fishes during the reproductive season and

this is traced to migratory activities of the fish and hormones responsible for

reproduction like the estrogen. They also harped on the fact that thyroid

hormone helps to increase the rate of absorption of some nutrients in the guts

thereby enhancing feed conversion efficiency and growth. Similarly, one major

effect of the thyroid hormones is its ability to increase the action of other

hormones like the growth hormones. NRC (2009) showed that a prolactin

hormone affects the diurnal variation of plasma fatty acids in Pacific salmon

fish. These high blood fatty acids can suppress feed intake as common to other

farm animals. The activities of prolactin are believed to be activated by

thyrioxinic or cortisol hormones and this hormonal circle in fish endocrine

system affects feed intake. It is further added that a variety of fish species shows

appreciable changes in plasma insulin level in response to fluctuation in plasma

nutrients. However, the possible influence of insulin and other hormones like

cholecystokinin (CCK) and cerebrospinal fluid insulin are associated with feed

intake and nutrient assimilation. Helene and Richard (2006) confirmed that

cholecystokinin (CCK), gastrin releasing peptide (GRP), ghrelin, glucagons-like

peptide, insuline and leptin are the peripheral factors controlling feed intake.

With the exception of gastric releasing ghrelin, all others serve as satiety signal

to reduce meal size feed intake and feed behaviour.

One other physiological factor that control fish feeding behaviour is the

metabolic activities that take place in the brain which is the Central Nervous

System. Some metabolites in the brain that have bearing to feed intake and

behaviour according to Wynne et al. (2005) are the neuropeptide Y (NPY),

orexins, melanocortins like proopimelanocortin (POMC),agouti-related protein

(CRH), melanin-concentrating hormones (MCH), etc. These peptide system

interactions with each other are very sensitive to signals from the periphery thus

allowing the hypothalamus to sense the status of energy usage and intake. The

Neuropeptide Y (NPY) structure is common in several fish including the catfish

10

and is found in the brain and gut. It is involved in the regulation of feed intake

in fish.

2.3.3 Feeds Factors

This involves the influence of the feed in its composition, size and texture,

forms, preparation, etc on the fish ability to accept the feed provided by the

farmers. Many feed factors have been identified to influence feeding behaviour

and feed intake of fish. Wilson (1994) and Lupatsch et al. (2001) confirmed that

level of digestible energy in a feed has control on feed intake as fish tends to

adjust feed intake in order to satisfy their energy need. It is reported that

Rainbow trout fed low energy feed grew at equal growth rate as those fed with

high energy diet by increasing their intake. It is confirmed that fish feed to

satisfy their energy need and metabolic energy need is the main controlling

factors (Lee and Putnam, 1973). Similarly, NRC (1983) showed that thiamine or

zinc deficiency in a diet can cause anorexia and this depressed state can lead to

reduction in feed intake by warm water fishes. In other words, feeds that are

deficient in nutrients based on expected feed regime of the fish at its expected

physiological state, lower feed intake. Another feed factor that can control feed

intake in fish is the size of the feed fed to the fish based on the size of the fish in

relation to the mouth size. NRC (2009) reported that growth was faster in

Atlantic Salmon fish fed with feed size with the diameter of 2.2 to 2.6 % of

their body length than those fed with feed of a particle size of 6-8% of body

length. It is further added that feed size below 2.2% body length lower feed

intake as the fish spend time in selecting feed to consume. In this direction,

Michael (1987) recommended that fish size of 0.02 to 0.25g be fed with 0.42 to

0.84mm pellet feed, 1.5 to 4.0g size be fed with 1.4 to 2.8mm feed size. Thus

feed intake will be higher on pellet feed than powder feed and it should be of

the right feed size. Presence of toxin in feed is another factor that determine

feed intake. These toxins can be from the manner the feed was stored after

11

processing and from the feed stuffs (Michael, 1987). Piper et al. (1982) reported

that oxidized fish and vegetable oil in formulated feeds can lead to low feed

intake by fish. Some of these toxins are the gossypol from cottonseed source,

protease from soybeans source afla-toxins from groundnut feed source, etc.

They also added that man made contaminants like pesticides, herbicides and

other chemicals present in feed can lower feed consumption by fish.

2.4 Fish Feeding Practice

Culturing fish under captivity for which pond and other aquatic

environment are inclusive, need sound and adequate feeding practice. This

feeding should be able to engender good feeds utilization and intake else slow

growth or death of stocks may eventually occur. Thus to have good growth and

break even in fish culture as a business, the form of the feed in use,

formulation, feed regime, ration size, time of feeding, prevailing water quality

and other factors should be well considered (Jonathan and Niall, 1988).

2.4.1 Forms of Fish Feeds and Feeding Stuffs

The use of formulated feed in enhancing fish productivity in pond is very

essential and these feed must be in the right forms of preparations. The

preparation of fish feeds are classified based on the moisture content of the feed,

feed buoyancy, shape, appearance and the stocks they are made for. Michael

(1987) said that feed preparation based on moisture content of the feed are

classified into dried, moist, wet feed and crumbs. That the dry feeds has about

10% moisture content, moist feed with 30-40% moisture contents and wet feed

above 50% moisture contents. In feeding practice, dry and moist feeds are very

common and have excellent result than the others. Again, dry feed are easily

made in large scale, easier to store, transported and fed to the fish than the rest.

Thus they are more palatable, attractive and easily ingested by the fish than the

wet and crumbs (Cruz et al. 2000).

12

On feed preparation based on buoyancy, there are the floating and the

sinking feeds. While the floating feed when fed float on the water, the sinking

feeds go down the water base. In whichever forms, both gives adequate growth

under normal condition. However, performances of floating feeds are high

though expensive. It is also reported that a mixture of 15% floating feed and 8%

sinking feed can be made (Zakes et al. 2006). These feeds in any moisture

content and buoyancy are in various shapes of pellets, crumbles, granules, balls,

cake etc and are fed to the fish based on the fish size also (Michael., 1987;

George., 1986 and Michael et al. 1999).

2.4.2 Fish Nutritional Requirements

Feeding fish can no doubt increase fish production. In feeding fish,

greater challenges exist than in feeding terrestrial farm animals as the feeding

behaviour of the farm animals can easily be monitored than fishes which dwell

in water. In feeding fish, the nutritional requirement changes with the

physiological changes that occur in the fish and in whichever stage, the fish

nutritional needs comprise protein, carbohydrates, fats, vitamins and minerals.

These in their formulation should be balanced to meet up with their growth need

and targets (Aqualex, 1996). Similarly, Cho (2004) added that feeding standard

which is the feeding practice employed to deliver nutritionally balanced and

adequate amount of diet to the fish to enable them maintain normal growth and

reproductive potentials together with efficient growth and or performance of

work should be high. Until now feeding of fish has been based on instinct and

folkloric practice and this has not met the nutritional requirement of the fish.

Quantitatively and qualitatively speaking, fish need protein of high value

of essential amino acids as fishes are efficient in the use of protein for growth

and reproduction. The dietary protein requirement of fish varies from species.

Rainbow trout (Salmon gairdneri) needs 40-60% of protein, channel catfish 30-

36%, carp (Cyprinus carpio) 38%, African catfish 35-45%, etc. The protein

13

requirement of fish is higher compared to other farm animals like poultry. This

is because they are naturally more efficient in eliminating nitrogenous waste in

the form of soluble ammonia compounds through the gills tissues directly into

the water and use less energy as a result of less activity, thus the proteins are

converted more to flesh (ADCP, 1980). It should be added that the protein need

of fish is influenced by various factors such as size of the fish, water

temperature, feeding rate, availability of planktons in the water, energy level of

the feed and the quality of protein in term of its amino acids composition. As

important as this nutrient is, its deficiency has been noticed. This ranges from

poor feed efficiency, poor growth rate to poor utilization of other feed nutrients

(Jonathan and Niall, 1988)

On the energy need of fish, Cho (1990) reported that energy is not a

nutrient rather it is an end product of absorbed macro nutrient when oxidized

and metabolized. It is added that most carbohydrate sources such as starch from

plant sources are not utilized as energy sources but as simple energy. Therefore

lipids and protein provide the energy need of the fish. Physiologically, lipids

and protein help to form important structures of the fish but the need for energy

can prevent their incorporation into the body tissue and may involve their

catabolism as source of energy. Thus, the utilization of the nutrients depends on

the level of intake and the make up of the diet. The over riding important of

food as an energy source means that the major factor regulating the food intake

of the animal is its energy value in relation to the animal energy need (Yinka et

al.2005). In the same vain, Jonathan and Niall (1988) added that the

carbohydrates consumed by fish are digested by several enzymes as in other

higher terrestrial animals. The mechanisms of using carbohydrate vary between

carnivorous and omnivorous species. Among the carnivorous species are the

carp, catfish, eel, etc which can ingest 80% starch as against carnivorous species

like Rainbow trout which are poor in starchy feed stuff utilization due to

inaction of several enzymes involved in digestion and catabolism of

14

carbohydrate. According to Graaf et al. (1995), the digestible energy need of

fry and fingerling is 3.0 - 4.0 Kcal/g, growers 2.5 - 3.5 kcal/g and broodstock

3.0 - 4.0 kcal/g. ADCP (1980) added that the energy need of fish depends on

temperature of the water, water flow, fish body size, level of feeding and water

chemical quality level.

Lipids are other nutritional need of fish. These are also source of energy

as 1g of lipid yields 9 kcal of energy. During digestion, lipids are broken down

into fatty acids and glycerol components which are absorbed by the fish. Body

fats are synthesized from excessive fatty acids and glycerol and are stored in the

subcutaneous tissue, muscle, space between connective tissue and abdominal

cavity (Michael, 1987). The deficiency of these nutrients has been linked to skin

discolouration, fin erosion, fatty liver, poor growth among other. Lipids tend to

deteriorate through oxidation producing substances that are toxic to fish and

destroy vitamin E. When fish feed are made with rancid fat (oxidized lipid),

incidence of muscular atrophy, weight loss and neutrality can result (NACA,

1989). Fish also need vitamins and minerals as nutrients for their normal

physiological function of growth and maintenance of body metabolism through

there enhancing of feed intake. These are specially included in the feed as

premix with varying composition (NACA, 1989; Graaf et al. 1995 and ADCP,

1980).

2.4.3 Fish Feeding Rates

Fish like other farm animals need feed to grow. This feed must be

balanced in nutrients and be well offered to the fish as poorly balanced feeds

cause more problem than the expected gains. This is one of the problems of fish

feeding. Feeding beyond that which the fish can consume is feed waste and it

also deteriorates water quality. Catfish will grow to their maximum endowment

when fed at near appetite capacity. They can grow efficiently when fed at 90%

of all they can eat voluntarily. This optimal level is generally achieved when

15

they are fed what they can eat within ten minutes feeding intervals (George,

1986). It is thus advised that the stock should be fed based on their biomass.

Michael (1987) opined that feeding rate should not be steady through out the

projected growing period of the fish. That the biomass feeding rate should be

adjusted as the fish grows. It recorded that fish of 5g be feed with 7.0%

biomass, 10g of fish with 6.7%, 15g with 6.3%, 20g with 6.0%, 50g with 5.0%

and 100g with 4.0%. In addition, Lovell (1989) indicated that farmers can feed

their stocks on a steady feed rate of 3 - 4% biomass, Davies et al. (2006)

reported the use of 5.0% biomass for catfish while Ruszynski (2003) reported

the range of 4 -8% biomass and that this rate depend on climatic photoperiod,

ration type and pellet size. The idea behind these various recommendations of

feeding rate is to avoid overfeeding as over-feeding leads to economic feed

waste, water pollution, low dissolved oxygen, increase biological oxygen

demand and increase pond bacterial load. Thus fish should be fed only the

amount they feed in a time not exceeding twenty five minutes feeding interval.

Steve and Helfrich (2002) harped on the use of extruded feed that afford the

observation of the fish while feeding. However, with the recommended feeding

rate, about 10 % of feed fed end up as waste, 10 -30% as faecal and liquid

waste. Of the remaining feed consumed, 50% of it is used for growth and 50%

for metabolic activities.

2.4.4 Feeding Regime

Feeding management is greatly influenced by two major factors; the

feeding rate and feeding regime. Feeding regime is the set time and frequency at

which the feed is administered to the fish in the presence of a prevailing

management condition (Aqualex, 1996). Feeding fish is labour intensive and

expensive, thus the feeding frequency is determined by labour availability, farm

size, cultured species and size of stock. Large catfish farms with many unit

ponds usually practice a once a day feeding due to time and labour, while

16

smaller farmers may feed twice a day. Generally, growth and feed conversion

increase with feeding frequency (Steve and Helfrich, 2002). This view was

collaborated by Mostafa et al. (2002), that feeding can be as many times as

possible within 24 hour time but their growth rate is greatly affected by time of

feeding due to voluntary feed intake of the fish and aquatic condition in which

the fish are being fed. George (1986), Michael et al. (1999) and Michael et al.

(2005) reported that feeding fish twice a day can be more advantageous. When

stocks are fed twice a day especially at the least time intervals of six hours,

catfish can eat and gain more weight than when fed once a day and they are

more voracious and vigorous in feeding. It is added also that feeding in the

morning hours is a good practice because the water temperature is usually low

and cool. It is also added that feeding after sun set should be discouraged

because of the incidence of high demand for oxygen by the fish for metabolic

activities and the competition for oxygen by the phytoplankton in the water for

their normal respiration activities at dawn. It is stated that the level of oxygen at

this time of the day (6.00 pm to 6.00 am) is low (Boyd, 1982). It has been

shown that once the time of feeding has been established in a production period,

it should be maintained as catfishes easily gets accustomed to regularity of

feeding time and feeding spots in the pond (Davies et al. 2006).

2.5 Stocking Rate

The efficiency of fish farming is also predicated on the stocking density

per unity area of the pond. Ella (1987) said stocking rate is the number of fish

stocked per square meter of the fish pond surface areas. Stocking rate depends

on the size of the pond, experience of the farmer, length of time of the

production period, expected production size, water supply, aeration process and

preparation to accept risk. George (1986) added that fish should be stocked

according to the surface area as over estimation of the area could lead to over-

stocking which also affect feeding, growth rate and water quality. According to

17

Michael et al. (1999) and Michael et al. (2005) stocking rate will reflect on how

much time and finance is dedicated to the stocks as it concerns feeding and

water quality management. There is therefore no fast and hard rule on the

stocking rate other than management process. To this end, the following is the

formula for determining the stocking rate of a pond.

Sr = W.ha x % mortality

Wf

Where:

Sr = Stocking rate

W.ha = Increase in weight per hectare

Wf = Weight gain per fish

% Mortality (not to exceed 20%). (Ella, 1987)

2.6 Pond Water Quality Management

The harnessing and manipulation of the fish ecosystem lies within the

prescribed unit of the water biological, physical and chemical aspect to produce a

good water quality for the fish. These excellent aquatic conditions guarantee fish

survival, growth and reproduction. The overall productivity of a water body can

easily be deduced by the primary productivity that forms the back bone of the

aquatic food chain and climatic condition and this plays a major influence on

pond water quality (Fast, 1983 and Dhawai and Kaur, 2002). Under this

condition, the most important factor of water quality that affects the production of

fish under a confirmed environment is those of the three factors of water quality,

namely the physical factors which include light temperature, colour and turbidity

of the water, the chemical factors which include the dissolved oxygen (DO),

hydrogen ion concentration (pH), hardness, salinity and alkalinity and the

biological factors which include the benthos and sediments, phytoplankton,

macrophytes and zooplanktons that exist as natural food of the fish. The natural

18

food is supplemented by artificial feeding unless in the case of the reconciliatory

pond production system and the use of other water holding materials that ensure

water flows (Onuoha and Nwadukwe, 1987; Yinka et al., 2005).

2.6.1 Physical Factors of Pond Water Quality

One major physical factors of pond water quality is the temperature of the

pond water. Temperature is the measurement of the hotness or coldness of a

body including water. It is the property of the body that defines the flow of heat

when it is placed in contact with another body. A 1g calorie of heat is required

to raise the temperature of the 1g calorie by 1oC. Forsberg et al. (1996) reported

that although fishes are sometimes called poikiothermic (cold-blooded), most

fish are ectothermal, which means that their body temperature is the same as the

surrounding water (tuna and a few other species have body temperatures

somewhat higher than the surrounding water, but they are not homothermal, that

is they do not have constant body temperature such as mammals or birds). The

body temperature of a eurythermal (wide range of temperature adaptation) fish

like largemouth bass may range from near freezing to nearly 90°F (32.2oC). It is

important to note that intrinsic differences exist in adaptation of fish to water

temperature. In regards to their temperature tolerance, fish are categorized as

coldwater, cool water, warm water, and tropical. Most tropical fish, such as

tilapia, die when temperatures are less than 50°F (10°C), and most salmonids

(trout and salmon) die when temperatures exceed 80°F (25.7°C). Channel

catfish, which are called warm water fish, survive from near freezing to about

90°F (32.2°C). Boyd (1982) added that the effect of water temperature that

enable optimal performance of fish varies among species as it dictate the feed

intake, movement, growth, breeding and the general metabolic activities of the

fish. In the same vein, Michael (1999) recommended temperature range of 21oC

to 31.9oC for tropical fishes. That at temperature beyond 32oc respiration will

be stressful, poor feed conversion and poor growth rate and same effect will be

19

noticed when temperature is below 21oC. Similarly, Michael et al. (2005) and

Fast (1983) showed water temperature affects biochemical reactions in water

and it determine the solubility of oxygen in the water. The higher the water

temperature, the lower the solubility of oxygen. The rate at which oxygen is

absorbed into the water is also a function of the depth of the water. The higher

the depth, the higher the oxygen solubility in the water. Again temperature

shock, which will stress or cause high mortality of fish, occurs when fish are

moved from one environment to another without gradual acclimation

("tempered") to the other temperature. Boyd (1995) and Edwin et al. (2009)

added that 0.2°C/minute (12°C/hour) can be tolerated provided the total change

in temperature does not exceed a few degrees. It is important to remember that

temperature controls the solubility of gases in water, and the reaction rate of

chemicals, the toxicity of ammonia, and of chemotherapeutics to fish. They

added that if water temperature is less than 10oC, stocks will cease to feed and

above 27oF stocks equally stop to feed. In freshwater, at sea level, the solubility

of oxygen is 11.3 mg/l at 10°C, but only 9.0mg/l at 21°C. Solubility of oxygen

also decreases with elevation.

On pond stratifications, Fred and James (2001) reported that pond

temperature stratification is a phenomenon that can be detected when diving

into a large pond or lake. The water temperature may drop drastically within a

few feet of the surface. In contrast, a well-mixed pond will have an almost

uniform temperature gradient when measured from the surface to the bottom.

Pond temperature stratification often occurs when the surface water is heated or

chilled. For example, a pond may undergo temperature stratification in summer

months as radiant heat from the sun warms the surface water. From the surface

down to a significant depth there is little change in water temperature, yet in the

next few inches or feet, the water temperature drops rapidly, then stabilizes to a

lower temperature range as the bottom is reached pond stratification can be

disrupted by rapid changes in temperature and strong winds; two events that

20

occur regularly in the spring and late fall. The physical action of strong winds

can cause mixing of water at the surface with the water at lower levels. Cold

temperatures can chill the surface water to a temperature lower than that found

at lower depths, causing it to become denser and sink to the bottom. One term

for this event is called turnover. Pond turnover is a seasonal event in healthy

ponds that redistributes nutrients in the pond.

Another important physical water quality worthy of note is the water

turbidity and colour. Turbidity and colour of pond water are other limnological

physical quality of pond water. Turbidity is the decrease of ability of water to

transmit light ray normally caused by either suspended colloidal material of

various size, coarse dispersion, and organic matters in the form of planktons.

Turbidity is also seen as an opaque or unclear appearance imparted to water by

the presence of suspended foreign particles (soil, plankton, etc.) Turbidity can

also be viewed as the measure of the clarity of water. The resultant effect of its

inability to transmit light tells on the colour of the water (Onuoha and

Nwadukwe., 1987 and Ysi, 2001). Colour of pond water that comes from

inorganic matter can be as disadvantageous as they not only hinder light

transmission but also reduce the phytoplanktons’ photosynthetic rate thus

reducing pond water productivity as the sediments in the water absorbed

phosphorus element from the water. The inorganic matters also destroy

benthoses, lower dissolved oxygen, clog fish gills and block moving fish vision

thereby causing stress to the stocks (Fast, 1983).

In aquaculture, turbidity can be noted by physical examination but can

accurately be done through the use of secchi disk and/ or turbid meter. Turbidity

has a great relationship with water colour. When pond water colour is clear or

bluish, it shows that plankton volume is low with low productivity. When it is

yellow or/brownish, it shows dissolved organic suspense with low dissolved

oxygen. Where the water colour is greenish, it depicts high plankton volume

and productivity (Suk et al., 1998; Howerton, 2001). Turbidity that causes low

21

pond productivity arising from organic suspense are caused by run off from

unstabilized water shed such as cropped land, road, etc. and by the source of

water used for the pond. Thus turbidity can be prevented by good land use

practices on the water shed or by construction of diversion ditches round the

pond, maintenance of good clean source of water, filtration of water into the

pond, establishing of good grass cover round the pond which can serve as

natural water filtration or rip raping mechanism if turbidity persist. It could be

removed with the application of aluminum sulphate (filter Alum) at the rate of

22.7kg/acre. This should be distributed over the pond surface by spraying the

dissolved alum on the pond surface with little agitation possibly during and after

application in a calm and dry weather (Daniel, 2003). It is further added by

Bryan et al. (2000) that when the turbidity is of soil colloid resulting to muddy

water, that this can be caused by wave stirring up from the pond bottom

sediments and this could be corrected by spreading a layer of hay or straw over

the pond bottom from the edge to a few feet’s from the shore. However, this

preventive measure should be with some caution as this straw or hay application

decomposition could lead to oxygen depletion. It is further advised that

correction of water turbidity can be possible through the use of 453kg of

agricultural limestone (CaCO3) or 335kg of hydrated lime per acre. These

chemical applications can keep turbidity of colloidal material for one to two

years. The use of quicklime is however discouraged as it could lead to fish kill.

2.6.2 Chemical Factors of Pond Water Quality

According to USDA (1996), dissolved oxygen is probably the most

critical factor of water quality that affects fish production. Fish require oxygen

for respiration, which physiologists express as milligram of oxygen consumed

per kilogram of fish per hour (mg/l). The respiratory rate increases with

increasing temperature, activity, and following feeding, but decreases with

increasing mean weight. Onuoha and Nwandukwe (1987) and Boyd (1982)

22

outlined several important implications of oxygen on the physiological facts for

aquaculture. It is stated that at a given temperature, smaller fish consume more

oxygen per unit of body weight than larger fish; or said in another way, for the

same total weight of fish in a tank, smaller fish require more oxygen than larger

fish. That actively swimming fish consume more oxygen than resting fish. In

raceways, high exchange rates will increase energy expenditures for swimming,

and oxygen consumption and that oxygen consumption of fish will increase

after feeding. Multiple feedings regime per day (3 or more) will result in less

variation in oxygen demand than once to twice feedings per day.

Daniel (2003) opined that in ponds, the major source of oxygen is from

algal photosynthesis and from wind mixing the air and water. In tanks or

raceways, oxygen is supplied by the inflowing water, which should be near

saturation for the temperature and elevation. In many trout hatcheries, the water

is re-used, that is it typically passes through a series of raceways (usually not

more than 4), with re-aeration (oxygenated) by atmospheric contact as the water

passes from raceway-to-raceway, or, re-aeration may be obtained with

mechanically powered aerators or air diffusers supplied by air blowers.

Whenever air is in contact with the water, whether through natural or artificial

means, a transfer of oxygen from the air to the water takes place until the water

becomes saturated. Plants under light convert carbon dioxide to oxygen in the

water. Fish, plants at night, and aerobic bacterial action consume the oxygen.

(Gary, 2007)

Cruz et al. (2000), Davies et al. (2006) and NRC, (2009) added that a

common generalization about oxygen requirements for aquaculture is that the

minimum dissolved oxygen should not be less than 5 mg/l for growth of warm

water fish and 6 mg/l for coldwater fishes at their optimum temperature. Thus,

for a raceway or circular tank, oxygen of the effluent water should be at least 5

mg/l. The oxygen available for fish is the difference between the inflow of

oxygen and the outflow of oxygen concentration. If the outflow must be no less

23

than 5 mg/l, then the inflow must be higher than that for fish to have any oxygen

for respiration. At a temperature of 15.5°C, oxygen saturation would be about

9.6 mg/l at 1000 feet, which would provide about 4.6 mg/l of atmospheric

oxygen for fish respiration (9.6 - 5.0 = 4.6 mg/l). The oxygen requirement for

100 kg of fish that consume 300 mg of oxygen per kilogram per hectare would

be 30,000 mg of oxygen per hectare (100kg fish x 300 mg/kg/h). At

temperatures optimum for growth, fish are stressed at oxygen concentrations

less than 5mg/l. If the condition is chronic, fish stop feeding, growth slows

down, stress-related disease begins. For rainbow trout, mortality may begin at 3

mg/l, but channel catfish tolerate less than 2 mg/l before mortality commences.

However, if the gills of fish are damaged by parasites, the fish may die when

oxygen concentrations drop only slightly below 5mg/l.

On the effect of oxygen on the performance of fish in the pond, Norm,

(2000) had shown that the minimum limiting oxygen concentrations for a fish is

dependent upon its genetic makeup, water temperature, level of activity, long

term acclimatization, and stress tolerance. Water with an oxygen concentration

of less than 3 mg/l will generally not support fish. When concentrations fall to

about 3 - 4 mg/l, fish start gasping for air at the surface or huddle around the

water fall (higher concentration points). Bio-converter bacteria may start to die

increasing the production of nitrogenous related compounds which compound

the lack of oxygen for the fish. Levels between 3 and 5 mg/l can normally be

tolerated for short periods.

On the balance of oxygen in a pond, Fred and James (2001) and Piper et

al. (1982) maintained that the oxygen content of a pond or lake is never

constant. Oxygen is continuously being produced by algae and other aquatic

plants and by wind and wave action. It is removed from the system through

respiration of aquatic animal organisms, by the biological oxygen demand

(BOD) of organisms such as bacteria that break down non-living organic

material, and even by a chemical oxygen demand (COD) caused by decay of

24

dead plants and animals. A frequently misunderstood phenomenon is how algae

affect oxygen concentration in a pond during day and night hours. Algae and

other plants are consumers as well as producers of oxygen. Algae produce

oxygen during the daylight hours and then consume it at night. During the day

algae use energy from the sun to drive a chemical reaction

Boyd (1979) and Fred and James (2001) added that it is not difficult to

get all the air into the water that the fish need. Oxygen is continually transferred

into the water at the surface of the pond and normally only a small water fall

will bring the pond water to or near to saturation. Heavily populated ponds may

need supplemental air and ponds with a large amount of algae may need

supplemental air at night when the plants are not making oxygen but consuming

it. It is very important that sufficient circulation is provided within the pond so

that all areas have proper oxygenation. Although the algal bloom benefits the

life in the pond, it must be controlled or will result in the loss of aquatic animals

such as fish and crustaceans. Oxygen problems in warm water ponds often

occur when the microscopic algae are either absent or overly abundant. If the

phytoplankton is absent, there may not be enough oxygen produced from other

sources such as wind and/or macrophytes in the pond to support a good

population of fish. However, if an algal bloom becomes excessive, it often has

three pronounced negative effects on the oxygen concentration and animal life

in a pond. The first negative effect of excessive phytoplankton in a pond is the

result of the cyclic events of algal respiration that occur over a 24-hour period.

An excessive algal bloom will produce an abundance of oxygen during the day,

often resulting in at or near saturation of oxygen in the water. At night,

however, the same excessive algal bloom consumes a near equal quantity of

oxygen during dark phase respiration. The oxygen concentration in the pond

may drop to a level that causes stress or death in a population of fish. This often

occurs at night or during the early morning hours before the algae can replace

the lost oxygen through photosynthesis. This may be complicated by several

25

days of cloudy weather that reduce the level of daytime photosynthesis.

Nighttime respiration will continue at the same rate with lower oxygen levels in

the pond, but there will not be enough daytime photosynthesis for the oxygen to

be replaced. Boyd (1979) and Chakroff (1978) added that the fluctuation of

oxygen is such that has low concentration of dissolved oxygen in the morning

time, high concentration in the afternoon and low again at dusk. Oxygen

depletion resulting in fish stress and loss is a common occurrence in ponds

during the hot summer months as the pond heats up and reduces the oxygen

holding capacity of the water. If this occurs along side with an excessive algal

bloom and/or cloudy weather, oxygen loss is usually significant, and the onset

of oxygen depletion is rapid (Michael et al 1999).

A second common effect of an excessive alga bloom on a pond is sudden

death of the phytoplankton population. This can occur for a number of reasons

including depletion of nutrients used by the algae, a seasonal change in water

temperature, high winds that turn over the water in the pond, rapidly chilling of

the surface waters, and destruction of the phytoplankton bloom with algaecides

during periods of hot weather. Although individual members of the

phytoplankton community are microscopic, the sum total of the community

makes up a large biomass in the water. If the phytoplankton biomass is suddenly

killed, it will sink to the pond bottom and rapidly decompose. The BOD created

by bacteria decomposing a high-density phytoplankton community is

significant. The combination of the absence of oxygen producing plant

community and the additional BOD that results from a decomposing algal

population can strip enough oxygen from the water to kill a fish population

(Masser and Wurts, 1992).

Pond water pH and alkalinity are other chemical factors that can affect

the performance of fish in a pond, the overall productivity of the pond and the

economic out lay of the farm. The combinatory features of these chemical

factors affect each other. The pH range of pond water is a product of the

26

fluctuation range of alkalinity and hardness of the rater. Pond water pH is the

negative logarithm of the hydrogen ion concentration in the water. It is the

potential hydrogen present in the water. This pH range is usually given as 1 to

14. A pH of 7 indicates a neutral condition (neither acidic nor basic). This is

where the hydrogen ions equal the hydroxide ions in concentration. A pH below

7 indicates more hydrogen ions than hydroxide ions and it is an acidic

condition. Above pH 7, there are more hydroxide ions than hydrogen ions, it is

basic or alkaline (Boyd et al. 2002 and Norm, 2000). Similarly, Andrew (2007)

and Davies et al. (2006) showed that all living organisms including fish have

their own optimal range of pH where growth is at its best. The optimal pH for

catfish pond is 6.5 - 8.5 but Onuoha and Nwadukwe (1987) added that catfish

can survive the lowest pH limit of 4.5 - 5.0. That beyond this optimal range fish

will experience stress and there will be altered metabolic activities. It also

affects the production level of the plankton in the water. Andrew (2007) and

Michael et al. (2005) added that there is a fluctuation of pH and it is caused by

the consumption and production of carbon dioxide and other chemicals used in

the pond. Planktons remove carbon dioxide and other acidic substances during

the day from photosynthesis activities increasing the pH level during the day.

However, at night time pH tend to acidic level due to the respiratory activities of

all these microbes that produces more carbon dioxide which reacts with water to

form carbonic acid. Furthermore, where the pH level needs modification, the

use of chemicals such as lime of various types, gypsum, alum etc is

recommended (USDA, 1996).

Water pH is closely related to alkalinity but alkalinity is not same as pH.

Alkalinity is the amount of buffering materials in the water. It is the measure of

bases mostly of ions of carbonates (CO32-

) and bicarbonates (HCO3) in the water

expressed in milligram per litre (mg/l) equivalent of calcium carbonate

(CaCO3). These act as buffers to keep the pond water pH stable. (Michael et al

2005 and Howerton, 2001). These bicarbonates and carbonates are derived from

27

the free carbon dioxide reaction due to carbon dioxide solubility in the pond

water. Free carbon dioxide is very soluble in water with variability from

temperature of the pond water. Its solubility is higher at lower temperature and

lower at higher temperature. For example at 0oC, solubility is 1.10mg/l, at 5

oC

it is 0.91mg/l, at 10oC it is 0.76mg/l, at 25

oC it is 0.58mg/l, at 30

oC it has

0.42mg/l, etc. On the reaction with pond water, carbon dioxide entering the

water produces carbonic acid (H2CO3) which dissociates to release hydrogen ion

(H+) and bicarbonate (HCO3). The bicarbonate on its part dissociates to give

more free hydrogen (H+) and carbonate ions. Carbonate and bicarbonates have

also been derived from the nature of the water shed and soil sources. Naturally,

water contains more carbonate than that which comes from ionization and this is

due to the constituents of the water and soil sources (Boyd, 1979; Boyd et al.

2002). Furthermore, Norm (2000) and Howerton (2001) added that carbonate

and bicarbonate can also be derived from bacteria dissimulation. As pond water

stratified, anaerobic condition could be created and bacteria that are present give

off nitrite, ammonia and other nitrogenous compound which react with carbon

dioxide to produce carbonates and bicarbonates. Boyd et al. (2002) went further

to give the relationship between total alkalinity and soil/ water pH. That total

alkalinity of below 5.0 mg/l equal pH below 5, at 5 - 10mg/l, it is 5.0 to 5.4 pH,

at 10 - 20mg/l it gives 5.5 to 5.9 pH at 20-30mg/l it gives 6.0-6.4 pH and 30 -

50mg/l of total alkalinity gives 6.5 to 7.0 pH. On this basis, total alkalinity

below 20mg/l which give below pH 5.0 can result to fish stress and death. Thus

liming before fertilization is strongly advised so that there can be the increase of

availability of carbon dioxide for plankton photosynthetic activities, raise the

pH to neutral or slightly alkaline value, increase the alkaline reserve in the water

and mud which prevent extreme change in pH, promote bacteria activities that

can beak down ammonia to nitrite, precipitate suspended or soluble organic

materials, decrease biological oxygen demand (BOD) and increase light

penetration (Martin et al., 1999).

28

Other important chemical factors of pond water quality are the presence

of nitrogenous compounds in the form of ammonia, nitrite and nitrates. Andrew

(2007), Ruszynski, (2003) and Hargreaves and Tucker (2004) said that the

major source of ammonia in a water of a heavily stocked culture pond is from

the uneaten feeds fed to the fish especially from those feedstuffs high in protein

contents like fish meal, Soya beans etc and bone meal or other mineral

supplementations. Other sources are the byproduct of the protein metabolism

released as gas through the gills and other nutrients entering the water which

bacteria can act upon e.g. solid waste and urea. What is measured by chemical

analysis (Nessler method) for ammonia is called total ammonia nitrogen (TAN)

because it includes two forms of ammonia: the unionized ammonium (NH3) that

is toxic and ionized ammonium (NH4+) and it is non-toxic. Ammonia should not

be detectable in a pond with a "healthy" bio-converter. The ideal and normal

measurement of ammonia is zero. When ammonia is dissolved in water, it is

partially ionized depending upon the pH and temperature. The ionized ammonia

is called ammonium and is not particularly toxic to the fish. As the pH increases

and the temperature drops, the ionization and ammonium decreases which

increases the toxicity. As a general guideline for a water temperature of 21oC

would be expected to tolerate an ammonia level of 1 mg/l for a day or so if the

pH was 7.0, or even as high as 10.0 if the pH was 6.0. At a pH of 8.0, just 0.1

mg/l can be dangerous. Optimum concentration of 0mg/l is advised. Norm

(2000) added that the effect of it is that it tends to block oxygen transfer from

the gills to the blood and can cause both immediate and long term gill damage.

The mucous producing membranes can be destroyed, reducing both the external

slime coat and damaging the internal intestinal surfaces. Fish suffering from

ammonia poisoning usually appear sluggish, often at the surface as if gasping

for air. It also reduces feed consumption, create stress and poor growth.

Robert et al. (1997) also informed us that nitrite is another form of

nitrogenous compounds that enters a fish pond after feed is digested by fish and

29

the excess nitrogen is converted into ammonia, which is then excreted as waste

into the water. Total ammonia nitrogen is then converted to nitrite (NO2) which,

under normal conditions, is quickly converted to non-toxic nitrate (NO3) by

naturally occurring bacteria. Uneaten (wasted) feed and other organic materials

are also broken down into ammonia, nitrite, and nitrate in a similar manner.

Nitrite should not be detectable in a pond with a properly functioning bio-

converter. Thus the ideal and normal measurement of nitrite is zero. A low

nitrite reading combined with a significant ammonia reading indicates the

ammonia-nitrite biologic converter action is not established, while a low

ammonia reading with a detectable nitrite reading indicates that the nitrite-

nitrate bacterial conversion activity is not yet working (Andrew, 2007 ).

On the effect of nitrite to fish, Norm (2000) and Michael et al. (2005)

revealed that Brown blood disease occurs in fish that are raised in water with

high nitrite concentrations. Nitrite enters the bloodstream through the gills and

turns the blood to a chocolate-brown color. Haemoglobin, which transports

oxygen in the blood, combines with nitrite to form methemoglobin, which is

incapable of oxygen transport. Brown blood cannot carry sufficient amounts of

oxygen, and affected fish can suffocate despite adequate oxygen concentration

in the water. This accounts for the gasping behavior often observed in fish with

brown blood disease, even when oxygen levels are relatively high. Nitrite

presence also damages the fish nervous system, liver, spleen, and kidneys of the

fish. Even lower concentrations over extended periods can cause long term

damage. Short term, high intensity, "spikes" which often occur during a bio-

converter startup or restart may go undetected yet cause problems to develop

within the fish months later. A common indication of a fish that has endured a

severe nitrite spike in the past is that the gill covers may be slightly rolled

outward at the edges. They do not close flat against fish's body. Fred and James

(2001) opined that Nitrite problems are typically more likely in closed, intensive

culture systems due to insufficient, inefficient, or malfunctioning filtration

30

systems. High nitrite concentrations in ponds occur more frequently where

temperatures are fluctuating, resulting in the breakdown of the nitrogen cycle

due to decreased plankton and/or bacterial activity. A reduction in plankton

activity in ponds (because of lower temperatures, nutrient depletion, cloudy

weather, herbicide treatments, etc.) can result in less ammonia assimilated by

the algae, thus increasing the load on the nitrifying bacteria. If nitrite levels

exceed that which resident bacteria can rapidly convert to nitrate, a buildup of

nitrite occurs, and brown blood disease is a risk. Although nitrite is seldom a

problem in systems with high water exchange rates or good filtration, systems

should be monitored year-round and managed when necessary, to prevent

severe economic loss from brown blood in any fish culture facility.

On Susceptibility of fish species to nitrite toxicity, Robert et al. (1997)

identifies largemouth and smallmouth bass, as well as bluegill and green

sunfish, as fish species that can resist high nitrite concentrations. Catfish and

tilapia, for example, are fairly sensitive to nitrite and trout and other cool water

fish are sensitive to extremely small amounts of nitrite. Goldfish and fathead

minnows fall in between catfish and bass in their susceptibility to brown blood

disease resulting from high nitrite levels. Striped bass and its hybrids appear

sensitive to nitrite, but little is known about the relative sensitivity compared to

other species.

Similarly, Boyd (1979) indicated that nitrate is another nitrogenous

compound in pond. Nitrate is produced by one of the autotrophic bacterial

colonies by combining oxygen and nitrite. This occurs both in the bio-converter

and to a lesser degree on the walls of the pond. A zero nitrate reading, combined

with a non-zero nitrite reading, indicates the nitrite-nitrate bacterial converter

action is not established. Concentrations from zero to 200 mg/l are acceptable

but should normally be below 100mg/l as high nitrate levels will both stimulate

and suppress spawning activity. Where ammonia and nitrite were toxic to the

fish, nitrate is essentially harmless. If the nitrate concentration gets too high, the

31

nitrite-nitrate converting bacteria may not be able to do their job effectively

resulting in a raised nitrite level (Bryan et al. 2000). Nitrate is the end result of

the nitrification cycle and is very important to plants in their life cycle. It would

take 100 days or over three months, (longer with any water change outs), for the

nitrate levels to build up to the 100 mg/l level. The nitrate concentration is

controlled naturally through routine water change outs and to a lesser degree

through plant/algae consumption (Norm, 2000).

32

CHAPTER THREE

MATERIALS AND METHODS

3.1 Location

The experiment was carried out in the Fisheries Unit of the Teaching and

Research Farm, Department of Animal Science, University of Nigeria, Nsukka.

3.2 Materials

The experiment was carried out using twelve plastic tanks measuring

0.6m x 0.6m x 0.9m. Two hundred and forty post juvenile African catfish

fingerlings (Clarias gariepinus) weighing 15.0 ± 0.26 g were randomly divided

into four treatment groups with 60 fish per group. Each group was replicated

three times with 20 fish per replicate. The fish were fed with extruded

commercial feeds of Catco Fish Concentrate. The composition of the diet is

presented in table 1. Other materials used include Jenway Portable pH Meter

Model 350, Jenway Portable Dissolved Oxygen Meter Model 970, thermometer,

sensitive scale, meter rule, 5mm mesh size net and dechlorinated water.

Table 1: Nutritional composition of the experimental diet

S/N NUTRIENTS % COMPOSITION

1 Crude Protein 42.0

2 Crude Fat 13.0

3 Crude Fibre 1.9

4 Ash 9.5

5 Phosphorus 1.1

6 Vitamin A 15000 I.U./kg

7 Vitamin D3 2000 I.U./kg

8 Vitamin E 200mg/kg

9 Vitamin C ( Stable) 150mg/kg

10 Copper 5mg/kg

33

3.3 Management of the Experimental Fish

The post juvenile African Catfish fingerlings were purchased from the

local hatchery in Makurdi, Benue state. They were randomly divided into four

treatments groups and fed with the commercial feed (Catco® fish Concentrate)

for one week acclimatization before the experiment commenced. To mitigate

the environment as a result of the exposure of the plastic materials to

atmospheric temperature, and the volume of the water used for the experiment,

an open shed was constructed with rough thatch over the water holding vessels

with its sides rounded up with wire mesh up to three feet high to prevent the

entrance of rodents and human factors.

The fish were fed daily with 1.5mm to 4.5mm feed size of the extruded

commercial feeds at 3% body weight throughout the twelve weeks experimental

period. The initial body weight (gm) and length (cm) of the fish were taken

using sensitive scale and meter rule, respectively before they were stocked and

subsequently at two weeks interval. Also measured were the temperatures of the

water using the thermometer and the pH using the pH meter before the daily

feeding practice. The dissolved oxygen was monitored and measured weekly

using the dissolved oxygen meter. The volume of the water was maintained at

0.18m3. The top of the vessels was also covered with 5mm mesh size net to

protect the stocks from jumping out while the water in the vessels was changed

bi-weekly to avoid the build up of nitrates and nitrites as effluent leaching was

not possible due to the use of plastic materials.

34

3.4 Experimental Procedures

The experiment has four treatments with three replicates which were as

follows:

T1: Fish in this group were fed once daily in the morning at 07.30 hour to

08.30 hour at 3% of their body weight.

T2: Fish in this treatment were fed once daily in the afternoon at 12.30 hour

to 13.30 hour at 3% of their body weight

T3: Fish in this group were fed once daily in the evenings at 17.00hour to

18.00hour at 3 % of their body weight.

T4: Fish in this treatment were fed twice a day in the morning and evening at

07.30 hour to 08.30 hour and at 17.00 hour to 18.00 hour respectively at

3% of their body weight. The feed used for treatment 4 was divided into

two so that the fish receive half of the ration in the morning and the

remaining half in the evening.

3.5 Parameters measured during the Experiment

The following parameters were measured

1. Live weight (g) of the fish using sensitive top loading scale

2. Length (cm) of the fish using the rule meter

3. Feed in-take of the fish using sensitive top loading scale

4. Dissolved oxygen using the dissolved oxygen meter, water temperature

using the thermometer and water pH using the pH meter according to the

various treatments. Some of the data generated were used to calculate weight

gain and feed cost per Kg weight gain. Mortality was monitored and records

kept on daily basis.

35

3.6 Experimental Design

The experiment was carried out using completely randomized design

(CRD). Below is the mathematical model of the experimental design:

Yij = U + Ti + ∑ij

Where:

Yij = Individual observations

U = Population mean

Ti = Treatment effect

∑ij = Experimental error

i = Number of treatments

j = Number of replicates

Statistical analysis

Data collected were subjected to analysis of variance (ANOVA) as

described by Akindele (2004).

3.7 Calculations Live Weight Gain of Fish = Final body weight of fish – Initial body weight gain

of fish.

Total Length Gain of Fish = Final body length of fish – Initial body length of

fish.

Feed conversion ratio (FCR) = total feed intake (g)/total wet weight gain (g).

Protein Efficiency Ratio (PER) = wet weight gain (g)/total protein intake

Specific Growth Rate = Final body weight of fish – Initial body weight of

fish/No of Days reared.

36

CHAPTER FOUR

RESULTS AND DISCUSSION

4.1 Growth Performance of African catfish Fed at Different Time

Intervals

Data on the growth performance and body length of African catfish fed at

different time intervals are presented in Tables 2 and 3. Significant differences

(P < 0.05) were noticed in the feed intake and weight gain of the fish in the

various treatments. Final mean body weight was 223.63g (T4), 200.13g (T1),

196.33g (T3) and 168.17g (T2). The mean body weight gained was 208.97g

(T4), 184.83g (T1), 181.07g (T3) and 153.41g (T2) and the mean daily weight

gain for the period was 2.60g (T4), 2.20g (T1), 2.16g (T3) and 1.83g (T2). The

specific growth rate (SGR) also showed significant difference at (P < 0.05) with

mean value as follows: T4 (1.41) T1 (1.33), T3 (1.32) and T2 (1.26). These

results were due to the feed consumption rate of the fish that showed significant

difference (P < 0.05) in the same order. This shows that the feed fed to the fish

impacted the fish positively at the various time intervals of feeding. This is in

agreement with Davies et al (2006) and Odeyemi (2007) of the high

performance of the fish fed twice a day as there was efficient utilization of the

feed. However, there were no significant differences (P > 0.05) in the feed

conversion ratio with a range of 1.23 - 1.30. This result agreed with the result of

0.98 -1.46 recorded by Hecht and Appelbaum (1988). The feed conversion ratio

of 1.23 was observed in treatment T4; also support that of Mostafa et al. (2002).

This high performance is attributed to the high quality of the extruded feed used

for the experiment whose nutritional composition and form conformed to the

prescription by ADCP (1980), Jan (1995) and Zulfiker (2001). Similarly, the

time of feeding also supported the growth performance of the fish. Nutritionally,

feed intake of fish is controlled by three factors which are the environmental

factor, the fish physiological factor and the feed factors. So long the same feed

37

was used in the various treatments, feed factors should not be considered to be

the reason for the observed significant differences. Biswas and Takeuchi (2003),

Kasumya (1999) and NRC (2009) reported that environmental factors in

relation to feeding time and water physico-chemical quality have a marked

impact on the feed intake of the fish as they can affect the fish physiological

endowment capable of creating all sort of stress and neuro-endocrinological

imbalance (Wynne et al. 2003).

4.2 Body Length of African catfish Fed at Different Time Intervals

As shown in Table 3, the length of the fish showed no significant

difference (P > 0.05) in all the various treatments. The final mean total body

length (cm) of 31.2cm (T1), 29.7cm (T2), 31.0cm (T3), and 32.0cm (T4) and

the total gain in length of 20.7cm (T1), 19.9cm (T2), 21.0cm (T3) and 22.0cm

(T4) did not contradict the observed body weight gain of the fish within the said

short period of the experiment. However, differences in total body length could

have begun to appreciate with more time as observed by Marc and Jean (1991)

and Hengsawat et al. (1997). There was no significant difference (P < 0.05) in

the mortality rate in all the treatments. The mortality rate was observed as

follows: 13.38% (T1), 11.67% (T2), 10.00% (T3) and 13.3% (T4). The

observed mortality values in all the experimental treatments were traceable to

handling stress during weighing and change of water. This same scenario was

also recorded by Davies et al. (2006). The recorded mortality was within the

production range of 10-20% reported by Graaf et al. (1995) and was not due to

any pathological disease conditions.

4.3 Physico-chemical Characteristics of Treatments Ponds

As shown in Table 4, there were significant differences (P < 0.05) among

treatments water temperature. The difference may be due to environmental

condition. The water temperature was highest in treatment T2 followed by T3

38

and T4. The least value was recorded in treatment T1. These observed water

temperature value also were in line with the findings of Odeyemi (2007) and

was attributed to the level of the water in the experimental tanks that affected

the assimilation of heat since the tanks were exposed for atmospheric sunlight

and heat (Boyd, 1979). However, the recorded temperature range of 25.5oC to

28.10oC is within the tolerable range for catfish production in the tropics but

with minimal metabolic effect fluctuation (Yeamni et al. 2007; Boyd, 1982).

While the pH level in all the treatments stood at pH 7.1 showing no significant

difference (P > 0.05), the dissolved oxygen value were at 7.1, 6.8, 7.3 and 7.5

for T1, T2, T3 and T4 respectively. The physico-chemical properties obtained in

the experiment were within the tolerable values for catfish production. Davies et

al. (2007) Cruz et al. (2000), Boyd (1982), NRC (2009) and Michael (1999)

showed that the dissolved oxygen and pH in pond should not be below 2.5mg/l

and pH of 5.0 - 8.0 for catfish production. The observed significant differences

(P < 0.05) in the growth rate of the fish could be traced to the difference in

water temperature thus causing stress. In Table 2 it was observed that T2 has

mean final body weight of 168.7g and temperature of 28.10oC. The water

temperature differences could have altered the metabolic activities within the

fish. Jan (1995) explained that there are differences between metabolic energy

for production (MEp) and metabolic energy for body maintenance (MEm). The

ratio between these levels of energy varies within body weight and water

temperature due to the interactive effect of feeding level and temperature on the

fish body weight. Similarly, Ali (2006) reported that temperature affects the

growth rate of fish by affecting a variety of metabolic processes including

respiration, feed intake and digestion. That, any divergence from the normal

ranges of the metabolic processes could alter the optimal range for fish health

and growth. Although, the feed consumption may be high but greater proportion

could have been used for body maintenance.

39

TABLE 2: Growth performance of African catfish fed at different time intervals

Treatments

Parameters T1 T2 T3 T4 SEM

Initial number stocked 60 60 60 60 -

Final stock density less mortality 52 53 54 52 0.41

Initial mean body weight (g) 15.1 14.5 15.2 14.5 0.26

Final mean body weight (g) 200.13b

168.17c 196.33

b 223.63

a 3.74

Mean body weight gain (g)/ fish 184.83b 153.47

c 181.07

b 208.97

a 3.74

Average daily weight gain (g) for the period 2.20b 1.83

c 2.16

b 2.60

a 2.58

Specific growth rate (SGR) 1.33b 1.26

c 1.32

b 1.41

a 0.02

Mortality 8.0 7.0 6.0 8.0 2.04

Mortality % 13.3 11.67 10.00 13.33 2.04

Total feed consumed per treatment (g) 13512.2b

11297.5c 13372.7

b 14268.3

a 0.57

Mean daily feed consumed (g)/ fish 3.09b 2.54

c 2.95

b 3.27

a 0.03

Feed conversion ratio (FCR) 1.30 1.27 1.26 1.23 0.21

Protein efficiency ratio (PER) 1.96 1.94 1.93 2.09 0.04

Mean with different superscript on the same row differ significantly at 5%.

39

40

TABLE 3: Body length of African catfish fed at different time intervals

Treatments

Parameters T1 T2 T3 T4 SEM

Initial mean length (cm) 10.5 9.8 10.0 10.0 0.28

Final mean length (cm) 31.2 29.7 31.0 32.0 0.48

Mean length gain (cm) 20.7 19.9 21.0 22.0 0.18

TABLE 4: Water temperature, dissolved oxygen and pH at different time

intervals

Treatments

Parameters T1 T2 T3 T4 SEM

Water temperature (OC) 25.50

c 28.10

a 26.43

b 26.13

b 0.14

Dissolved oxygen in water (mg/l) 7.1 6.8 7.3 7.5 0.10

Water pH 7.1 7.1 7.1 7.1 0.17

Mean with different superscript on the same row differ significantly at 5%.

TABLE 5: Cost implication of feeding the fish at different time interval

Treatments Parameters T1 T2 T3 T4 SEM Total cost of fish at N600.00/Kg 6,243.60

b 5,346.54

c 6.360.84

b 6,969.00

a 0.01

Total cost of feed at N300.00/Kg 4,053.66a 3,389.25

c 4,011.81

b 4,280.79

a 0.33

Profit margin (N) 2,189.94 1,957.29 2,349.03 2,688.21 0.01

Profit margin % 54.10 58.06 58.73 62.9 1.98

Feed cost per Kg weight gain (N) 390.00 380.00 379.00 368.00 0.72

Mean with different superscript on the same row differ significantly at 5%.

41

4.4 Cost Implication of Feeding African catfish at Different Time

Intervals

Table 5 shows the economic aspect of the various treatments used in

the experiment. The cost implication of feeding the fish at the various

treatments levels showed a significant difference (P < 0.05) for the total cost

of fish at the prevailing market price with the highest value of N6,969.00 for

T4, N6,360.84 for T3, N6,243.60 for T1 and N5,346.40 being the lowest for

T2. There was also a significant difference (P < 0.05) among treatments in

total cost of feed consumed by the fish in the course of the experiment. The

value of N4, 280.79 was recorded for T4, N4, 053.66 for T1, N4, 011.81 for

T3 and the lowest value of N3, 389.25 for T2. The observed significant

differences (P < 0.05) in the total cost of feed consumed were as a result of

the different body weight gained of the fish in accordance to their different

feed of the fish. However, the profit margin percentage recorded ranged

from 54.10% to 62.90% showing no significant differences (P > 0.05). This

observed marginal profit percentages agreed with the 40-60% range of

profitability recorded by Adebayo and Adesoji (2008) and Davies et al.

(2006). This means that though there were significant differences (P < 0.05)

in the cost of the fish and feed used, the profit recorded were still high and

that the feeding methods used were also economical. There were also no

significant differences (P > 0.05) in the feed cost per kilogram weight gain

of the fish as their values ranged from N390.00, N380.00, N379.00 and

N368.00 for T1, T2, T3 and T4 respectively. This was due to the profit

margin recorded which lie also within economic level.

42

CHAPTER FIVE

SUMMARY AND CONCLUSION

5.1 Summary

Fish feeding is one of the enormous tasks the farmer is faced with if

the fish must grow. This is because of the relationship between the feeding

and the water quality as they affect each other during the cause of

management. The practice of feeding is far from being an exact science. It is

a highly subjective process. Edwin and Meughe (2007) and FAO (2005)

reported that though catfish has been cultured over the years and it ranks the

most popular cultured fish in Nigeria, their is a considerable alteration in the

feeding behaviour of the fish ( Brown, 2008). Recently, Edwin et al. (2009)

argued that the best time of day to feed fish is still an object of debate.

Nevertheless, they opined that the time of day to feed fish is largely dictated

by the logistics of feeding practice. It has been shown that the most dictating

factors are the water quality of the pond considering the fact that the time of

day has a good bearing on the water temperature, pH and dissolved oxygen

in addition to feeding management. Thus the response of the fish to time of

feeding and its acceptance is not static as it’s nocturnal habit make up has

been broken due to the practice of domestication. It is therefore evident from

the result obtained in the present study that catfish should be fed twice daily;

morning and evening time of the day. However, it is pertinent to consider

when the prevailing physico-chemical characteristics such as water

temperature, pH, dissolved oxygen, nitrate and other nitrogeneous

compounds, etc that affect feeding behaviour are at optimal level in the

pond.

43

5.2 Conclusion

With the result obtained from the experiment, the growth performance

of African catfish is highest when fed twine a day; morning and evening

compared to other time of the day. However, in determining best time of the

day to feed catfish, other factors such as stocking density, stocking

integration and aggression, feed composition, feeds size, fish forms and feed

preparation should also be considered. It is also necessary to consider the

fish physiological factors such as neuro-endocrinological state that affects

the response of fish to feeding as well as its growth performance (NRC,

2009; Colgan, 1993).

5.3 Recommendations

The results of the experiment showed that feeding fish in the

afternoon (T2) resulted in reduced feed in-take, reduced weight gain,

increase in water temperature and decrease dissolved oxygen. The

significant increase in the water temperature and decrease in dissolved

oxygen might have put stress on the fish, thereby leading to low feed in-take

and reduced weight gain. It is evident from the superior performance of fish

in treatment 4, that the best time to feed African catfish is in the morning

and evening.

44

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