Is Aquaponics Cruel To Fish?

When aquaponics fish only function as the provider of plants with the nutrients they need, it is safe to say that no cruelty is inflicted on them. In fact, this model mimics the ecosystem.

On the other hand, when fish are reared with the goal of earning money by selling them, this is a form of animal exploitation that can be labeled as animal cruelty. Animal rights groups oppose such activity.

What fish work well with aquaponics?

Freshwater fish are the best candidates for any aquaponics setup. A good reason for this is that this type of fish is easier to manage and more accessible. Below are the most recommended fish for aquaponics:

  1. Tilapia
  2. Carp
  3. Trout
  4. Catfish
  5. Salmon
  6. Koi
  7. Perch
  8. Goldfish
  9. Barramundi
  10. Bass
  11. Cod
  12. Angelfish
  13. Guppies
  14. Blue gill

You may read this post to learn more about the species of fish that you may place in your aquaponics fish tanks.

Does aquaponics harm fish?

The answer to this question all depends on the purpose behind setting up an aquaponics system. If the goal of aquaponics is to consume fish and vegetables, then this system harms fish. From the perspective of ethical veganism, this is unethical.

Ethical vegans oppose any form of animal exploitation which includes rearing animals to meet human needs, such as becoming their food supply. If you want to learn more about the relationship between aquaponics and veganism, read this post. (Insert link)

On the other hand, if the aquaponics practitioner only grows and sells vegetables and fruits, allowing the fish to thrive in the fish tanks without intending to sell them, this kind of system does not harm the fish. In this setup, the fish are not harvested to be sold as food or ornamental. They are just reared because their wastes act as nutrient sources for the plants in the aquaponics grow bed.

Aquaponics is one natural way of rearing fish because this approach mimics the ecosystem. Aquaponics represents the interaction of water, aquatic life, bacteria, nutrient dynamics, and plants as what nature intended it to be.

Aquaponics, inspired by nature, leverages the power of bio-integrating these different components:

  • Exchanging the waste by-product from the fish as a meal for the bacteria
  • Turning into a perfect fertilizer for the plants
  • Returning the plants the water to the fish in a clean and safe state

Consequently, you grow fish similar to their natural habitat, and therefore the fish is not harmed unless they will be exploited by selling them for profit's sake.

How to avoid fish overpopulation in aquaponics?

Even though aquaponics can be harmless to the aquatic animals in the system, this does not mean that their well-being will not be jeopardized. Specific issues that may compromise the fish's health should be looked out for. One of which is fish overpopulation.

Overpopulation, commonly known as overcrowding, happens when the number of fish in the tanks has reached its limit. This situation exposes the fish to several diseases and should be avoided at all costs.

If you have a smaller fish tank, suppose less than 50 gallons of water, the recommended stocking density is 1 inch of fish for every gallon of water. For example, a 10-gallon tank could hold ten fish with a length of one inch or five fish if the size is two inches.

Another approach for stocking density is per five to ten gallons of water is equivalent to one pound of fish. Now, remember to not stock more than 1 pound of fish for every three gallons of water. This will dramatically raise the risk for fish stress, fish infections, and an overall imbalance of your aquaponic system.

How to decrease stress on fish in aquaponics?

Stress is a condition in which an animal cannot sustain a normal physiologic state due to different causes adversely affecting its well-being. Therefore, it is imperative to decrease the factors that could lead to fish stress.

Below are the causes and symptoms of fish stress in an aquaponics setup:

Rapid breathing
Poor water quality
Presence of physical injuries
Bully fish companion
Fish is at the water surface, gasping for oxygen
Low level of dissolved oxygen
Erratic swimming behavior like resting at the surface or bottom of the tank
pH level fluctuating
Rubbing or scraping the sides of the tank
High levels of ammonia, nitrite, and other toxins
Fish exhibit poor appetite
Irregular water temperature
Fish swim erratically
Poor fish handling, noise or light disturbance
Fish' fins are clamped towards their body; the presence of physical injuriesMalnourishment and overcrowding

The key to stress prevention is appropriate management, including good water quality, diet, and cleanliness.

Feed the fish a high-quality meal that matches their nutritional needs. Each species has its dietary requirements, which differ from one another. Supplementing diets with fresh vegetables and live food is a practical way to give a complete diet of fish with unknown nutritional requirements.

Here are other steps you can observe in addressing fish stress:

  1. Install a filter or a settlement tank if your system's water contains visible particulates.
  2. Ensure your pH, ammonia, nitrites, and nitrates are all within acceptable limits.
  3. Make sure there is enough aeration.
  4. Feed fish at the proper rates and remove any uneaten food after each feeding.
  5. Identify the presence of bully fish and remove them from the tank.
  6. Reduce the frequency of opening and closing the tank lid and scooping fish out of the tank for inspection (only as needed).


Animal cruelty is a controversial topic today, and many food production methods are being put into question because these exploit animals to meet human needs. Aquaponics, which is a way of producing food, can be flexible regarding the issue of animal cruelty.

As noted in this article, aquaponics may be cruel-free to the aquatic animals present in the system as long as they are not reared for commercial purposes (e.g., sold as food or bait). Here, the fish help the plants grow healthy through their biological wastes while the plants filter the water that returns to the fish tanks. Apparently, there is a symbiotic relationship between the two organisms; neither is harmed nor abused.

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