Fish Health and Disease in Aquaponics: What You Need to Know

Fish health and disease in aquaponics is extremely important to understand and monitor as fish are the driving force of your entire system. If you’re a beginner, you’re going to want to learn as much as humanely possible, but just remember that aquaponics is truly a trial and error process and not everything is going to go plan. Take it one day at a time and be open to making mistakes!

As you start to build and experiment with your own system, you’ll quickly realize that fish disease in aquaponics is actually quite common, and make no mistake, you’re going to lose some fish. But don’t let a few dead fish discourage you from pursuing aquaponics. If you’re able to properly understand and appreciate the process and the needs of your fish, you can effectively maintain your fish, your system, and your water so that disease is kept to a minimum and your fish are as healthy and as happy as possible.

Here’s everything you need to know about fish health and disease in aquaponic systems!

Table of Contents

• What a Healthy Fish Look Like in Aquaponics
• The Causes and Symptoms of Fish Stress
• Types of Fish Diseases in Aquaponics
• How to Prevent Fish Disease in Aquaponics
• How to Recognize Fish Disease in Aquaponics
• How to Treat Fish Disease in Aquaponics

Fish Well-Being and Behavior

The best way to tell if your fish are unwell or unhealthy is to simply walk up to your tank and observe their behavior. If they’re healthy, they’ll behave normally, responding to your moves and interactions with them. If they’re unhealthy, they’ll show unusual behavior (like gasping for air or resting at the surface).

The best time to do a checkup is during feeding hours, as that’s when you interact with them the most and regularly observe their behavior.

Here’s what a healthy fish should look like:

• Fins and tails are extended and straight
• A heavy appetite and desire to eat; they shouldn’t back away from you if they know they’re about to be fed
• They should be swimming and moving around normally within your tank and not displaying any signs of lethargy (there are a few exceptions — such as catfish — that will sleep on the bottom or hide a little bit)
• Their eyes should be clear and shiny
• They shouldn’t be trying to obtain air or breathe from the surface of the tank
• There shouldn’t be any discoloration or streaks or marks along the sides of their body
• They shouldn’t be rubbing up on or scraping the sides of the tank

The Causes and Symptoms of Fish Stress

Stress is often caused by living in inadequate or less than optimal water conditions. When your water’s pH, temperature, or oxygen are out of the optimal range, then your fish will exhibit signs of stress. Additionally, the amount of food they receive (whether too much or too little) can cause stress as well.

When stress happens, it’s because your fish have to work harder to overcome poorer water or environmental conditions. This results in a poorer immune system where eventually, after continuous stress, your fish’s ability to fight disease is significantly reduced.

It’s important to remember that stress by itself isn’t enough to kill your fish, and fish (at least the fish used in aquaponics) are actually pretty hardy and can withstand small changes.

What they can’t tolerate, however, is an extended period of stress. If continuous stress occurs, they’ll undoubtedly develop diseases from various fungi, parasites, and bacteria. If this happens, then it’s very hard to get rid of and your treatment options are very limited.

On another important note, you also need to understand that when fish stress happens, there’s usually more than one reason. More often than not, there are several factors that are causing stress and any one of them can kill your fish. For proper care, evaluate your fish, do some trial and error, and take some notes so it doesn’t happen again.

Types of Fish Disease in Aquaponics

Fish disease solely happens because there’s an imbalance in your system. For your fish to survive and flourish, your system needs all three elements — your fish, your water, and your pathogens — to be in sync and balanced with one another.

If these three things aren’t in sync, then you’ll see two types of diseases spring up: diseases caused by abiotic factors and diseases caused by biotic factors.

Abiotic diseases are those that are caused by nonliving factors that are controllable, such as temperature and water quality, while biotic diseases are diseases that show physical evidence of a pathogen, such as fungal and parasitic diseases.

1. Abiotic Diseases in Fish

Despite what most people think when they hear the word “pathogens,” pathogens are not the primary cause of fish death. That number goes to abiotic diseases caused by less than optimal water conditions.

Abiotic Diseases in fish include:

1. Hypoxia
2. Temperature Stress
3. Ammonia Poisoning
4. Nitrite Poisoning
5. Hydrogen Sulphide
6. pH Imbalance
7. Improper Salinity
8. Gas Bubble Disease
9. Food Deficiency

2. Biotic Diseases in Fish

Pathogens are the root cause of biotic diseases in aquaponics and the three that you’ll see most often are bacteria, fungus, and parasites. All three of these pathogen groups enter your system through the surrounding environment, the transfer of fish, or are already present in your unit/setup.

How to Prevent Fish Disease

Proper care and maintenance is the best way to prevent fish disease. That means you need to monitor your fish on a daily basis and do your due diligence to ensure proper care.

Here are a few things you can do to prevent fish disease in your aquaponic setup:

• Don’t add unhealthy-looking fish to your system. If the fish doesn’t look good, then you can either isolate it and add it later, or not add it at all. Examine all of them for signs of disease.
• Make sure you get your fish from a respectable and proven hatchery.
• If you want to be on the safe side, it’s recommended that you isolate your fish in another tank for 45 days before adding them to your aquaponics tank.
• Giving fish a salt bath before adding them can remove unwanted parasites and treat early-on infections.
• Make sure that the water you’re using is clean and free of chemicals (like chlorine) or contaminants. Read our water quality guide to see what type of water you can use.
• Make sure your water quality parameters (DO, Oxygen, pH, etc.) are balanced and maintained.
• Don’t adjust your water parameters (pH, Temperature, ammonia, DO) too quickly. Small adjustments are a must.
• Make sure your biological filtration process (how your water moves and gets filtered through your system) is working, effective, and efficient.
• Provide the fish with a healthy balance of fish food and a proper diet.
• Keep dissolved oxygen levels as high as possible for proper aeration.
• Your fish feed can mold; keep it stored in a dry, cool, dark place.
• If you’re going to use live food, make sure that it comes from a reputable source or somewhere/something that you trust. Sometimes, live food can carry unwanted parasites and pathogens.
• Try to remove uneaten food that’s floating around or sitting at the bottom of your tank.
• Prevent or otherwise block small critters from entering your tank.
• Pets should never be allowed in the tank and grow areas as they can carry unwanted parasites with them.
• Don’t expose your tank to direct sunlight. Shade it as much as possible but don’t make it completely dark.
• Follow normal hygiene practices similar to those associated with normal farming (wash hands, cleaning, etc.).
• Guests and visitors should not handle the fish unless they’ve washed their hands.
• Never use one fishnet for several tanks. One fish net per tank will limit and prevent disease exposure.
• Keep your fish at peace. Loud noises, flashing lights, and vibrations can cause stress in your fish.

How to Recognize Fish Disease

If you’re properly monitoring your system, disease will show itself relatively easily. Just look for those tell-tale signs. Here’s a quick list of external and behavioral signs of fish disease.

1. External Signs of Fish Disease

• Your fish have black spots, white spots, visible ulcers, and discolored patches
• Eyes that are enlarged and popping out
• Lesions covering their body
• The fish looks swollen and bloated
• Body looks disfigured (jaw looks irregular, fish looks bent, etc.)
• Fins look ragged and disfigured
• Gills or fins appear to be decaying

2. Behavioral Signs of Fish Disease

• Fish aren’t eating, have a poor appetite, or are suddenly changing their consumption habits
• Fish are rubbing against the sides of the tank or scraping against them
• General lethargy that’s out of the ordinary
• Fish are floating or swimming irregularly and are having issues with buoyancy
• They are gasping for air at the surface of the tank

How to Treat Fish Diseases

When it comes to treatment, your options are pretty limited but there are a few that show promise.

• If all of your fish are showing common symptoms as a group, then it’s probably an issue with the water quality. Do your normal inspections of Dissolved Oxygen (DO), temperature, pH, etc. to see which one is off. After you’ve identified it, make the necessary corrections.

• If only a few of your fish are acting irregularly or showing signs of disease, then you need to remove them immediately so that the disease doesn’t spread. You can do that by putting them in a separate quarantine tank (sometimes called a hospital tank). Once removed, do a thorough inspection and look for signs of disease. Dispose of the fish once you identify the disease and take precautions with the rest of your tank moving forward.

• In certain situations and with certain fish, you can try giving them a salt bath. Because salt is toxic to pathogens, it should kill them in the event that they’ve infiltrated your fish. Take your fish and put it in a saltwater mixture (in a separate tank) with 2.2 pounds of salt per 26.5 gallons and leave it there for 20 to 30 minutes. After that time has passed, place them in another tank with a mixture of 1 to 2 grams of salt per liter and let them sit for 5 to 7 days.

Frequently Asked Questions

Is Aquaponics Bad for Fish Health?

No, absolutely not. Because aquaponics involves a naturally recirculating system and mimics a natural ecosystem, your fish are able to thrive (and most diseases are actually prevented because of the recirculation). As water is naturally filtered throughout your system, your fish are able to swim in a healthy, clean environment.

Can Fish Disease Spread to Humans?

Just like all animals, there are chances that germs from fish can carry over to humans and make people sick. However, reported fish illnesses from aquaponics or aquarium fish are very rare. General hygiene should prevent spreading anything.

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