TREATMENT OPTIONS FOR FISH IN

AQUAPONICS SYSTEMSALEX PRIMUS, DVM, PHD

UNIVERSITY OF MINNESOTA

COLLEGE OF VETERINARY MEDICINE

Overview

• Intro to Aquaponics

• Fish Health Management• Keys to Keeping Fish

Healthy

• Common Signs of Disease

• Common Pathogens of Fish

• Treatment Options • Regulatory Compliance

• Strategies to Minimize Harm to Biofilter

INTRO TO AQUAPONICS

Aquaponics: Conceptual Basis• Aquaponics = RAS Aquaculture + Hydroponics

• Recirculating Aquaculture System (RAS)• Enclosed intensive fish production

• Water filtered and reused

• Hydroponics• Method of growing plants in water (no soil)

• Requires nutrient supplementation

• NO3-, K+, PO4

3-, etc.

Aquaponics: Major Biological Components

• Aquatic animals (e.g. Fish)• Excrete ammonia as waste (primarily via the gills)

• Nitrifying Bacteria – “Biofilter” • Convert: Ammonia → Nitrite → Nitrate

• Plants• Nitrate consumption promotes growth → improves WQ for fish

Synergistic interactions between components contribute to the health and productivity of aquaponics systems

Fish Diversity in Aquaponics

An International Survey of Aquaponics Practitioners (Love et al., 2015)

FISH HEALTH MANAGEMENT IN AQUAPONICS

“AN OUNCE OF PREVENTION IS WORTH A POUND OF CURE”

- BENJAMIN FRANKLIN

Keys to Maintaining Good Fish Health

1. Always Maintain Good Water Quality!!!

2. Minimize Stress!

3. Good Husbandry & Nutrition

4. Good Biosecurity

5. Buy Healthy Stock

6. Quarantine / Entry Treatment

7. If Fish Get Sick, Get a Diagnosis

8. Ozone / UV Treatment of Water

9. Know Your Resources

10. Always Keep an Eye on your Fish

Common Indicators of Disease

• Fish going off feed

• Fish gasping at surface or staying near water inflow

• Abnormal behavior• Flashing, rubbing, etc.

• Lethargy, positioning, etc.

• Presence of any external (or internal) lesions• Erosions, ulcers, spots, fuzziness,

hemorrhages, etc.

• Increased mortality rates

Gross External Lesions

Infectious Diseases of Fish

• Parasites• External

• Internal

• Bacteria

• Viruses

• Water Molds

Common External Parasites of FW Fish

• Inhabit gills, skin and/or fins

• Most are Opportunistic Pathogens• Low numbers – asymptomatic• High numbers – morbidity &

mortality• Low → High typically due to:

• Stress & Poor WQ

• Clinical signs• Flashing, gross lesions, respiratory

distress, “cloudy” skin

• Diagnosis: ”Wet-mounts”

• **Treatment: Salt, formalin, potassium permanganate, copper, hydrogen peroxide, other

“Ich” – White spot

Trichodina

Monogenean

**Not necessarily legal for food fish and safe in aquaponics systems. More to come…

Common Internal Parasites of FW Fish

• Inhabit many tissues

• Generally asymptomatic

• Complex life cycles common• Snails, arthropods, birds,

mammals

• Includes several types of worms and a few oddballs

• Diagnosis: Necropsy +

• Treatment• Typically not required• No approved drugs for food

fish

Bacteria & Viruses• Many bacterial & viral diseases of fish

• Many species specific, others not

• Most difficult to identify based on clinical signs / gross morphology• Typically require advanced diagnostics

• Viruses• Most recognized are Primary Pathogens

• No drug-based treatment options

• Bacteria• Include both Primary and Opportunistic

• External – A few bath treatment options**

• Systemic – Medicated feed treatments**

• Internal focal / multifocal – hard to treat

**Not necessarily legal for food fish and safe in aquaponics systems. More to come…

Water molds – “Saprolegnia”• Often called “fungal infections”, but not true fungus

• Ubiquitous in freshwater and soil

• Very difficult to treat once established

• Because they are saprophytic, will start growing on fish that die in water – can be diagnostic “red herring”

• Early Diagnosis: ”Wet mounts”

• Treatment**: Formalin, hydrogen peroxide, other

**Not necessarily legal for food fish and safe in aquaponics systems. More to come…

TREATMENT OPTIONS FOR FISH IN AQUAPONICS SYSTEMS

Why is treating sick fish in an aquaponics system so challenging?• Limited number of approved drugs for fish

• Regulations are much more stringent for food fish

• Most basic treatment options could harm / kill your biofilter

• Other treatment options may be harmful to your plants

Pathogen Treatment Considerations

1. Make sure your in compliance with regulationsA. Feed-based antibiotics now require veterinary oversight

• Requires Veterinary Feed Directive, which in turn requires Veterinarian-Client-Patient-Relationship

• Technically no off label use allowed, which means certain drugs can only be used for infections with certain pathogens in certain fish species (mostly salmonids and catfish)• But FDA says if other guidelines being followed and it is needed,

enforcement species/pathogen specifics are not a priority

Pathogen Treatment Considerations

1. Make sure your in compliance with regulationsB. Bath treatment drugs/products should be FDA-approved

and used as indicated on the label, with some exceptions (ex. Salt considered low priority)• Any off-label use (i.e. different fish species or pathogen than

indicated on label) requires veterinary oversight

• For more on which drugs are approved for which pathogens, and other regulatory detail, visit: • https://www.fws.gov/fisheries/aadap/aquaculture.html

• Or just Google: Aquaculture Drugs and AADAP• Aquatic Animal Drug Approval Partnership - US Fish and Wildlife

Service

• Continued on next slide…

https://www.fws.gov/fisheries/aadap/aquaculture.html

Pathogen Treatment Considerations

1. Make sure your in compliance with regulationsB. Bath treatment drugs (continued)

• For Example, certain formulations of certain drugs/chemicals produced by certain manufacturers…• PARASITE-S (a Formalin formulation) produced by Syndel USA

• …is approved for treatment of certain indications in certain species of fish…• Control of external protozoa and monogeneans in all finfish

• …at certain doses for certain amounts of time• Up to 250 ppm for up to 1 hour (some exceptions, like more

detailed requirement for use in Salmonids, etc.)

• More details on label (not going to try bore you…any more than I already have)

Pathogen Treatment Considerations

1. Make sure your in compliance with regulationsB. Bath treatment drugs (continued)

• Some of this just regulatory, some very important for safety of fish and consumer

• Lastly, there are some other options for using drugs within compliance, but lots of details• For example:

• Investigational New Animal Drugs (INADs)

• Low Regulatory Priority (LRP) Drugs – LRP drugs are innocuous compounds that have historically been used in aquaculture but will likely never be approved by FDA. (ex. Salt)

https://www.fws.gov/fisheries/aadap/aquaculture.html#collapseFour1

Pathogen Treatment Considerations

1. Make sure your in compliance with regulationsB. Bath treatment drugs (continued)• List of FDA approved drugs

1. Chorionic Gonadotropin (Chorulon®)2. Formalin (Parasite-S, Formalin-FTM, Formacide-B)3. Hydrogen Peroxide (35% Perox Aid®)4. Chloramine-T (Halamid® Aqua)5. Oxytetracycline Hydrochloride (several products available)6. Tricaine Methanesulfonate (Tricaine-S)7. Florfenicol (Aquaflor®)8. Oxytetracycline dihydrate (Terramycin® 200 for Fish)9. Sulfadimethoxine & Ormetoprim (Romet® 30 & Romet® TC)

• Remember, some of these are only labeled for certain pathogens in certain fish species

• Be sure you know what you are allowed to do, especially for food fish

Pathogen Treatment Considerations

2. Most bath treatment options and antibiotics can harm your biofilter• Do what you can to minimize contact between these

drugs/products and your biofilter• A few strategies will follow on next slides

• In addition to these strategies, one can also mitigate risk by…• Minimize nitrogen load on biofilter around the time of treatment

• Can hold or decrease feed for several days

• Backup your biofilter if possible

Strategies to minimize biofilter-chemotheropeutant contact• Salt Dip for external parasite infections

• Remove fish from tank and place in smaller container with 10-30 ppt salt, then place back in tank• Can go up to 30 minutes if fish tolerate, but usually a dip is

much quicker (1-2 minutes at higher end of ppt concentration)

• Ensure fish getting enough Oxygen through process

• Ideally use NaCl, sea salt, solar salt• Don’t want additives such as anti-caking agents that are present

in many salts used for water softeners

Strategies to minimize biofilter-chemotheropeutant contact• Bypass/Isolate fish tank for bath treatment AND do

major water change to fish tank (50-75%) post-bath

Major Water Change in Fish Tank

Strategies to minimize biofilter-chemotheropeutant contact• Bypass/Isolate fish tank for bath treatment AND do

major water change to fish tank (50-75%) post-bath

Strategies to minimize biofilter-chemotheropeutant contact• Bypass/Isolate fish tank for bath treatment AND do

major water change to fish tank (50-75%) post-bath• Ensure:

• Dissolved oxygen levels sufficient during bath• Fresh water parameters matches replaced water as well as

possible

• Can also:• Continue replacing more water than usual in the system on a

daily basis• Put activated carbon filter in-line with system

• May need multiple treatments

Fish Health Resources• Books

• Ex. “Fish Disease: Diagnosis and Treatment”

• Websites• OIE Aquatic Code• FAO - Aquaculture• AFS – Fish Health Section• Regional Sites – NCRAC, SRAC• The Fish Site

• People• American Association of Fish Veterinarians• Aquaculture extension specialists• Diagnostic Labs – public and private

Questions