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Management Of The FreshwaterAQUARIUMThe common freshwater tropical fish is a hardy
creature and on the whole adapts very well to the
environmental changes to which it is subjected in theaquarium. This type offish is kept by thousands of
aquarists who have never measured the hardness orpH
of the water in their fish tanks, but to keep the more
delicate species or to breed the more difficult egg-layershe aquarist may have to modify the environmental
conditions. A basic understanding of water chemistry
will help him to carry out these modifications
successfully.
WATERParadoxically the source of fresh water is the sea.
The sun causes evaporation from its surface which, as
water vapour, rises into the atmosphere and forms
clouds. When clouds cool, their water vapour may beprecipitated as rain which picks up various impurities as
t falls through the atmosphere. These are very few if the
rain is falling on rural areas but over towns it picks upcarbon dioxide, sulphur dioxide, hydrocarbons, tars and
dust particles.
Once on the ground the water may dissolve
chemicals from the soil and the rocks through which it
passes. In limestone areas the water will dissolvecalcium salts and become hard (temporary hardness) or
may dissolve magnesium salts and become hard(permanent hardness). The main quality that most people
notice about hard water is that it will not lather soap
properly arid that it furs up kettles, but from the fish-keeping point of few, some fishes prefer soft water, for
example killifishes and characins, whereas others, such
as the Australian Rainbow (Melanotaenia nigrans) and
he Lake Nyasa cichlids, prefer hard water.Public water supplies which come from deep wells
are usually hard; water which comes from surfacereservoirs on moors and mountains is usually soft. In the
process of purifying water for human consumption thepublic water companies subject the water to a number of
chemical and mechanical processes. Minute amounts of
some of these chemicals remain in the water but the onlyone of importance to the freshwater fish keeper is
chlorine, added to most public water supplies as a
disinfectant. Chlorine in the free state disperses if leftstanding in the aquarium for twenty-four hours and
fishes, therefore, should not be put into newly filled
aquaria. Most freshwater tropical fish keepers use tap
water and this is satisfactory for keeping most fishes.
some species, however, and this is mentioned in
catalogue section under the appropriate entry, the wmust be soft or in rarer cases hard to keep
fishes in the best condition and to breed th
successfully.
Hardness can be measured in three different un
darks degrees (grains of calcium carbonate CaC
per UK gallon); German degrees DH (parts of C
per 100,000); or in parts per 1,000,000 of CaCO3
pre
in the water (ppm). The latter scale will be uthroughout this book. For comparative purposes 14 p
is approximately one darks degree or 0-8 DH.
CLASSIFICATION OF WATER BY PPM
SCALEDescription of water ppm
Soft 0-50
Medium soft 50-150
Hard 150-300
Very hard Over 300
Local water companies will supply informationthe hardness of the water in their area.
Gravel containing limestone or limestone rockw
will increase the hardness of water in the aquarium.
aquarist can measure the hardness of his tank water
the E.D.T.A. (Schwarzenbach) Method. This test cancarried out by any aquarist who has studied sim
chemistry at school. Chemicals for this test are availa
from most suppliers of laboratory chemicals.If the local water supply is hard, soft water may
obtained by collecting rainwater in plastic contain
from glass or plastic roofs via plastic pipes, providthe aquarist lives in an area with relatively unpolluair. Metal roofs or pipes may cause contamination. H
water can be softened by ion-exchange resins giv
demineralized water, or very expensive distilled wmay be purchased. Temporary hardness may
removed by boiling the water and filtering off
precipitated calcium carbonate. These soft waters better aerated for a few hours before placing fishe
them.
The acidity or alkalinity of the water he use
another chemical factor very important to the aquar
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This depends upon the concentration of hydrogen ionspresent in the water, of which the pH value is the
measure. Neutral water has a pH of 7, strong alkalis a
pH of 14, and strong acids a pH of 1. Water for fishkeeping is within the limits ofpH4 topH 9.
Most fishes which prefer soft water also prefer it to
be acid and water may be acidified by adding peat. It is
not recommended to add the peat directly to the tank asalthough it sinks to the bottom after a few days, it is
easily swished about by the fishes; it is better to add thepeat to the aquarium filter. Use a good sphagnum peatmoss and boil it in soft water for five minutes. Squeeze
out and discard the surplus water (this contains excess
humic acid from the peat) and put the peat in the fbetween two layers of filter wool. Running the f
gradually acidifies the aquarium water.
There are a number of fishes which live at mouths of rivers, in coastal waters and estuaries, wh
the water is brackish. Some authorities recommend
addition of one teaspoonful of salt (NaCl) per gallon
water when keeping these species in the aquariExamples of such fishes are the Scat or Ar
(Scatophagus argus), the Green Puffer Fish (Tetraofluviatilis) and the bumble bee fishes (Brachygobspecies).
Glass Catfish (Kryptopterus bicirrhus)
EQUIPMENT
Tanks - The best shape for fish tanks is rectangular with
he length two, three or four times greater than the depth.This gives the most common size of fish tank as
24x12x12 in (60x30x30 cm), although larger sizes
36x12x12 in (90x30x30 cm) and 48x12x12
(120x30x30 cm) are also common. The smallest for a community of small fishes is 18x10x10
(45x25x25 cm). Tanks of this shape offer a large surf
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area in relation to depth and allow carbon dioxideexpired by the fishes to be given off to the atmosphere
easily.
Smaller tanks can be moulded completely in glass or
plastic but the large tanks have angle iron or stainlesssteel frames into which the glass is fixed. The angle iron
must be painted to stop it rusting. The upper surface of
he angle iron on which the tank cover rests is mostsusceptible to rust and a good technique to prevent this is
o rub down the paint on the top surface as soon as a newank is bought and to paint the bare metal with two coats
of a cold galvanizing paint, finishing off with two coatsof good enamel paint in the same colour as the rest of the
ank. The stainless steel and nylon-coated angle iron
anks are both trouble-free in this respect. Homemade,all-glass aquaria, in which synthetic bonding agents are
used to fix the glass together, are another recent
nnovation.
Always put a glass cover on top of the tank; as wellas preventing fishes leaping out and evaporation, it stops
dust from gaining access. There are various tank coverswhich can be-placed on top of the cover glass to househe lighting arrangements.
Heating The majority of tropical fishes are happy at a
emperature of 72-78F (22-26C). Most aquarists use
he conventional immersed heater and separate immersedhermostat to provide this controlled temperature. The
mmersed thermostats are of two main types; one is
completely submersible and can be used in very shallow
anks but has to be taken out of the water to alter itssetting, and the other has a control at the top which
projects over the top of the tank. This type, therefore,
cannot be completely submerged but alterations to itssetting are easily made. External thermostats are also
popular these are either stuck or fixed by a stainless
steel clip to the side glass of the aquarium. They have the
advantage that their setting can be easily altered.
In recent years a few aquarists have used a base
heating system employing the metal-encased electric
heater used for greenhouse heating. This heater is placed
about 2 in (5 cm) under the tank and is connected to an
external thermostat, thus avoiding wires or heaters insidehe tank. Combined submersible heater-thermostats are
gaining in popularity.
Thermometers These are basically of two sorts; thoseusing the bimetal strip mechanism or those using alcohol
or mercury. The best type for the aquarium is a mercury
hermometer with the scale marked directly on the glass.Nevertheless, the experienced aquarist develops the habit
of touching the front of the tank with the back of his
hand, for with practice he can tell if the temperature isright thermometers have been known to go wrong.
Lighting Ordinary light bulbs, allowing 25 watts square foot of water surface area, for eight to twe
hours per day will give adequate lighting. The length
time depends upon the amount of daylight falling ontank and the plants the aquarist wants to grow.
Fluorescent lighting is becoming popular and in rec
years tubes emitting light of special wavelengths h
been specially developed for aquarium use. There hbeen criticisms of these tubes and the latest idea is to
both a fluorescent tube and incandescent bulbs at same time. Although fluorescent tubes are m
expensive initially than ordinary bulbs, in the long tthey are more economical because of their gre
efficiency and longer life.
Aeration and filtration Aeration by passing a streamair bubbles through the water helps to oxygenate
mainly by agitating the surface and allowing a be
exchange of oxygen and carbon dioxide. It also help
cause circulation of water within the tank. A good streof bubbles is easily produced by using an electric
driven pump and an air stone. The only real advant
of aeration is in tanks which are overcrowded and
normal aquarium should not need this aid.
Filtration filters from the water of the aquarium
particulate matter suspended in it and thus helps to k
the water crystal clear. However, not all fishes lik
crystal clear tank; many of the catfishes, for examlike a layer of sediment on the bottom. If the fi
material contains active charcoal some of the o
chemicals, including waste products produced by
fishes, are also removed. Modern filters help providbrisk circulation of water in the tank which fishes fr
running water enjoy but those from still water dislike.
Filters are of two main types, the box filter in whdirt is removed from the aquarium and the under gra
filter in which the sediment is sucked down into
gravel and subsequently broken up by bacterial actSome aquarists believe under gravel filters interfere w
the growth of aquarium plants.
PLANTS
One of the advantages of tropical freshwater tanks is the aquarist can grow plants in them. The function
plants in the aquarium is to provide decoration hiding places, and to give shade in some areas of
tank. Although plants give off oxygen during
daylight hours, this oxygen is small in proportion toamount that is transmitted through the surface layer o
properly shaped aquarium.
The genus Cryptocoryne consists of a number
favourite aquarium plants. They are bog plants in t
natural condition in South-east Asia but they also g
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very well when submerged. One of the most popular is
C. affinis, which can grow up to 12 in (30 cm) tall. C.
beckettii is another similar plant but not as fast growing.
C. blassii, which is a very intense dark red under the leaf,s a more recently discovered Cryptocoryne, growing in
popularity. Most of the members of this genus do notnsist on bright light but do better in soft acid water.There are a number of small-sized species such as C.
nevillii, which only grows to 2 in (5 cm).
The genus Echinodorus comes from America and
also contains broad-leafed plants. E. paniculatus, theAmazon Sword Plant, is a popular species, but needs
more light than the Cryptocorynes to grow well.
There are a number of fine-leafed plants such as
Cabomba caroliniana and Myriophyllum brasiliense
which are very attractive but in my experience either
grow so well that they continually need thinning or nevergrow at all.
The species with grass-like leaves, Vallisneria
spiralis and Sagittaria species, for example, are also
attractive and popular plants. Both genera grow well inwell-lighted aquaria with ordinary aquarium gravel as
compost.
The floating or top plants such as Lemna species(Duckweed) orSalvinia species do not grow well under
artificial light. The two species of the genus Ceratopteris
(Floating Fern), however, do very well under artificial
ight and their roots and leaves are very useful as a placefor the Anabantidae to anchor their bubble nests.
DECOREvery tropical fish hobbyist should have one tank
which he sets, up with the intention of creating a
beautiful and attractive piece of furniture in his home.
This tank should be at least 24x12x12 in (60x30x30 cm)and preferably larger so that he has scope for
aquascaping.
For this furnished aquarium it is a good idea to pthe ends and back of the tank black on the outside
provide a background which sets off the colours of
plants and fishes. Choose an attractively coloured graof a particle size of about 1/8 3/16 in (3-5 mm),
even though the gravel is sold as well washed, alw
wash it again. Choose your rockwork carefully; i
possible to buy rockwork but it is far better to find yown on the mountains, on rocky shorelines or
mountain streams. My furnished aquarium has sobeautiful red sandstone rocks found on the shore ofIsle of Skye. Do not use limestone rockwork in y
tank.
Plants are now needed to set the scene for the fishAquascaping is a very personal choice and I prefer to
only Cryptocorynes they do not require exces
light, they grow reasonably slowly so that the picture
the tank remains unchanging, and there is not constant necessity of having to thin out plants as w
faster-growing species. It is a good idea before setting
a furnished aquarium to have a look at other aquaritanks and at show tanks at major fish shows to find what appeals to you.
Finally the fishes are added, preferably all more
less of the same size and chosen so that they will all together peaceably. It is a good idea never to have
one fish of a species; if you have a few they alw
stimulate each other to better colour and more interesbehaviour. It is also advisable to have one species m
numerous than the rest, one of the small tetras,
example, such as the Cardinal Tetra (Cheiro
axelrodi) or Glowlight Tetra (Hemigrammus gracilis)these species shoal together so well. Include some l
bearers Red Platies (xiphophorus maculatus)
Swordtails (x. helleri) look well against the blbackground and also a couple of Sucking Loac
(Gyrinocheilus aymonieri). These are not chosen
their looks but because they will act as vacuum clean
and keep algae from growing on the glass and plants.Fishes are best fed daily, and at the same time
hobbyist can check that they all look well and heal
and also on the temperature of the water and that it lo
clear. About every three to four weeks the front gmay need to be scraped with a razor blade scrape
algae are found growing there. From time to time it m
be necessary to siphon off any collection of mulm onbottom and to top up the water to replace evapora
losses. This is a lot less care and attention than m
other pets require and fishes do not suffer damage if unattended for two to three weeks when the aquaris
away on holidayfishes in good condition come to
harm if left without food for this period of time.
Tropical Freshwater plants - 1 floating fern; 2 Cryptocoryne;
3 Amazon Sword; 4 Cabomba; 5 Valisneria
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