What Makes A Right Fish?
Not all fish species are suitable for aquaponic culture. The fish need to be able to:
• Thrive in crowded conditions.
• Be resistant to fluctuating dissolved oxygen levels, as well as nitrate saturation and pH fluctuations.
• Be resistant to diseases and parasites.
• Use nutrients efficiently, which leads to rapid growth.
• Be edible or ornamental.
Types of Aquaponic Fish
Tilapia is probably the most widely kept aquaponic fish, and has become a synonym for aquaponic aquaculture. What makes it a so well-suited is its medium size, hardiness, good tolerance to a variety of temperatures and water conditions, easy spawning, and neutral, soft meat.
Tilapia are also known for their hearty appetites and fast growth. On a side note – they are also quite good looking fish.
Trout belongs to the salmon family, and their flesh is highly prized. They are coldwater predators that prefer optimum temperatures around 15 °C, and require high-protein diet and clean water.
Because of their high preference for colder temperatures, they are ideal in cold or temperate climates. Some growers grow trout only during winter months. Note that due to the cool water the choice of plants for growing might be more limited.
The most commonly kept species is the Rainbow trout (Oncorhynchus mykiss).
Two species of catfish, Channel catfish (Ictalurus punctatus) and African catfish (Clarias gariepinus) are a great addition to an aquaponic system because of their high tolerance to fluctuating oxygen, nitrite and pH levels, and their resistance to parasites and disease.
These bottom-dwellers will need sinking food, and because they lead static lifestyles lying at the bottom of the tank, they are considered a low-density fish. They can be grown in combination with species which swim in the upper water layers.
Carp is probably the most widely cultured fish in the world.
In aquaponic setting, all three common species of carp: Common carp (Cyprinus carpio) Silver carp (Hypophthalmichthys molitrix), Grass carp (Ctenopharyngodon idella) can be grown together, because that way they will cover all food niches, providing a better use of food resources and therefore less poorly-dissolvable waste. They can survive in an amazing temperature range (4-34 °C / 39-93 °F), with upper half of the 20s°C (~ 77-84°F) being the preference for fast growth.
Although largemouth bass is more sensitive than Tilapia, it still has a high tolerance for fluctuating dissolved oxygen levels, and resistance to high nitrate levels. Largemouth bass thrives within different temperature ranges which makes it a great year-round fish.
Ornamental fish such as koi and goldfish are also a good choice, especially if you are only starting your system and want to test it, in the case you are not keen on using fish as a food source, and there is a market for ornamental and pet fish in your region.
In Australia, commonly grown native species include Barramundi, Silver Perch and Murray Cod.
Although exclusive invertebrate farming is rare in aquaculture, aquatic invertebrates can be a great addition to a fish tank. For example, prawns consume uneaten fish food, fish waste and other organic material in the tank, helping to support a healthy system and increasing the rate of waste decomposition.
Important note: Whatever species of fish you choose to grow, never release any of them into waterways! I would always recommend choosing a fish species native for your region.