Fish For Aquaponics (5 Common Questions Answered)

Choosing which fish to add to your aquaponics system is an exciting decision! Fish play a crucial role in aquaponics and some species are better than others when creating a successful ecosystem!

When choosing which fish to add to an aquaponic system, it’s very important to choose fish that are not only aesthetically pleasing to look at, but beneficial for the system as a whole. It’s possible to raise a variety of fish in an aquaponic system. But, some are simply better than others and many require specific conditions to thrive! In this article, we will cover common questions asked when it comes to adding fish to aquaponic systems. Read on to find out more!

Fish For Aquaponics

Aquaponics combines growing plants hydroponically and aquaculture. Aquaculture is raising fish! In aquaponics, fish, and plants are raised in the same balanced environment. A symbiotic ecosystem is achieved in a successful aquaponic system between plants, fish, and microorganisms. 

fish for aquaponics 1
Aquaponics combines growing plants and fish together in the same system.

Aquaponics takes the natural cycles of fish and puts them to good use! It just so happens that the eating and producing waste that fish do works wonders for growing plants.

Fish waste is the perfect fertilizer for cultivating a variety of different plants. When an aquaponics ecosystem has reached its peak establishment, the plants thrive!

The fish provide the plants with a natural source of organic nutrients through their waste byproducts, microbes convert the waste into nutrient sources for plants, and the plants then naturally filter the water.

(You can learn about plants that filter water here.)

All of this together provides a clean living environment for the fish, microbes, and plants to flourish in!

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In a symbiotic relationship, plants use fish waste as fertilizer and clean the water for the fish.

The most common plants to grow in aquaponic systems are leafy lettuce, kale, swiss chard, microgreens, radishes, carrots, beets, basil, mint, chives, watercress, broccoli, cauliflower, and cabbage.

There are many more plants that can thrive in an aquaponic environment but leafy greens and herbs are the easiest and fastest growing choices. 

How Many Fish Do I Need For Aquaponics?

The ideal number of fish for your tank is based on the size of your tank and the size of your fish. A good rule of thumb is that for each inch of fish, they need at least a gallon of space.

For example, if you have a 20-gallon tank, then 20 one-inch fish is the maximum number you could have to maintain a healthy environment. 

fish for aquaponics
For each inch of fish, try to have a gallon of space.

For larger fish, each fish should be allocated 5 gallons of space. The bigger the fish, the more space they require to grow and move around freely.

But, depending on the exact species of fish that you choose, you should do your research to determine exactly how much space they need to thrive. 

Do Aquaponic Fish Need Light?

Aquaponic fish do not require light. The only reason fish need light is to be able to see their food. Therefore, the natural sunlight cycle is perfect for your aquaponic fish.

Aquatic creatures are naturally sensitive to light. Therefore, there is definitely such a thing as too much light for fish.

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Aquaponic fish do not need an artificial light source if they have sunlight.

The microbes in your aquaponic system also do not require light to thrive. The only thing in the aquaponic system that needs light for survival is the plants themselves.

Ensuring your plants receive the proper amount of sunlight is very important so that they can properly photosynthesize.

Which Fish Is Best For Aquaponics?

When considering the best fish for hydroponics, it’s important to think about which fish will best suit your specific aquaponic system. The best fish for an aquaponic system depends on the size, temperature, and location of the system.

It is also important to consider the type of plants the system will grow. Tilapia, catfish, goldfish, tetras, bass, cod, salmon, perch, trout, and sunfish are among the top choices.

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Goldfish are just one possible choice for the fish in an aquaponic system.

In an aquaponics system, fish plays a critical role as it produces the natural fertilizers needed by the plants to thrive. It’s important to remember that the fish will not achieve a balanced ecosystem all on their own.

Proper management and care for the system are essential for a successful aquaponic system. But, a good first step is determining which species of fish will best suit your specific setup.  

What Small Fish Are Best For Aquaponics?

The best small fish for aquaponics are guppies, tetras, and goldfish. These small fish are low maintenance while still great at providing nutrients to your aquaponic ecosystem.

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Guppies, tetras, and goldfish are some of the best small fish for an aquaponic system.

Read on for a deeper dive into raising guppies, tetras, and goldfish!


The male guppy reaches approximately .6 inches to 1.4 inches long. The female guppy roughly grows to 1.2 inches to 2.4 inches long. Guppies prefer water temperature ranging from 72°F to 78°F. For your fish to thrive, the optimal pH range is between 6.7 to 8.5.


This fish approximately grows up to 1.5 inches long. They prefer water temperatures ranging from 70°F to 81°F. When it comes to pH range, the Tetra Fish require the level maintained at 6 to 7.


When you keep goldfish in small fish tanks, they grow to be roughly 1 to 2 inches long and will not exceed more than 6 inches. However, Goldfish which are living in the wild may mature up to 12 to 14 inches long. These fish prefer water temperatures between 65°F to 72°F. Their ideal pH range is between 7.2 to 7.6. 

Fastest Growing Fish For Aquaponics

Most fish take a couple of years to grow to be full size. Even comet goldfish that are known to grow fast take 2-3 years to reach full size! But, there are one species of fish that is perfect for aquaponic hobbyists who also want to harvest the fish for eating. 

Tilapia is a popular choice for larger-scale aquaponic systems. Not only are these fish edible and adaptable but they also have fast growth rates! Tilapia mature faster when compared to other fish species. Tilapia has a growth span of roughly 9 months from finger size to ready-for-harvest. 

Tilapia grow fast compared to other species of fish. For example, trout take roughly 4 years to reach their mature size.

fish for aquaponics
Tilapia is a fast-growing fish that is popular in aquaponic systems.

Salmon takes about 2 years to reach harvest-ready size. Tilapia is a truly fast-growing fish which is why they are so popular for aquaponic systems!

The ideal temperature range for tilapia is between 37° – 86° F. For their optimum health and growth, their preferred pH is >6 with low ammonia and nitrite levels.

Additional advantages to growing tilapia in aquaponics include: 

  • Tilapia are resistant to diseases and parasites.
  • They are adaptable and can handle a wide range of water quality and temperatures. 
  • They can survive longer in a toxic water environment with low oxygen or high ammonia levels.
  • Tilapia is easy to breed.
  • Tilapia grows faster than most other cultured fish.
  • They are tolerant of overcrowding in the fish tank.
  • They are omnivorous and enjoy diets composed of animals and plants, therefore  expensive fish food is not necessary.
  • Tilapia are delicious when cooked. 

Can You Eat Fish From Aquaponics?

Some people are surprised to hear that aquaponic systems are good for more than just growing plants. If your aquaponics system is big enough, you could also grow edible fish!

Many people opt for inedible fish that simply produce nutrients for the plants and live for long periods. Others love the idea of growing both plants and fish to eat through the same sustainable system. 

If eating the fish from your aquaponic system is your goal, choosing the right fish is extremely important. Of course, you can’t eat goldfish despite how large they can grow!

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You can eat fish from aquaponics, including tilapia, salmon, trout, perch, and catfish.

The most popular edible fish for aquaponic systems are tilapia, salmon, trout, perch, catfish, barramundi, and largemouth bass. These fish require large aquaponic setups.

Outdoor ponds or pools are the best options for aquaponic hobbyists looking to eat the fish they raise.

Although smaller fish like guppies and goldfish are technically edible, they are so small that it is difficult to properly clean them. If fish are not cleaned properly before eating, the bacteria can be dangerous and harmful. Therefore, larger fish that are easier to clean and serve is ideal. 


Having fun with your aquaponic system is the most important element. It’s exciting to begin the journey to having your own self-sufficient ecosystem that also provides food! Aquaponics is a great way to get creative and make the system your own; especially when choosing the best fish for you!

You can learn about some plants that grow well in aquaponics here.

You can learn more about the differences between hydroponics and aquaponics here.

You can learn more about the benefits of hydroponics here.

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About the author:
Sofi is a passionate writer who studied communications and environmental studies at Eckerd College. You can get in touch with Sofi at

Sofi L.

Jon M

Hi, I'm Jon. Let's solve your gardening problems, spend more time growing, and get the best harvest every year!

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