Welcome to Part 2 of our ‘Which Aquaponic Fish’ guide. To read Part 1, view here.
The catfish (pictured above) is the most commonly cultured fish in the United States because it grows fast, is easily available and is a popular food. Catfish are bottom dwellers, so they are raised well with other species of fish that occupy the mid or upper levels of a tank. A combination of Catfish and Bluegill works well if you want a variety in your aquaponic fish, as they have similar needs in terms of temperature and water quality.
Raising Catfish alone can be tricky, as it is difficult to get enough total fish weight as they like to stay on the bottom and you physically can’t fit enough on the bottom (unless you have a large shallow tank.)
Dissolved Oxygen – Catfish do well at levels above 4mg/L. At levels below this they may not eat and will be vulnerable to parasites and disease.
Temperature – This is a warm water fish, and will grow most efficiently between 21 – 32°C
Feed – In most farming set-up’s, Catfish are fed a low protein pelleted food. A Catfish largely detects food with tastebuds all over its body as well as inside the mouth.
Growth rate – A large Catfish fingerling can grow to 1 pound in size in 5 months if kept in ideal conditions.
Koi are a domesticated variety of the common carp. Generally grown as an ornamental fish due to their beautiful colouring and unique patterns, they are usually considered a pet rather than an edible fish source, however they can be eaten.
They can be an great choice for an aquaponic fish farmer due to the high price they sell for. They sell at a significantly higher price for their ornamental value than for their food value. They are also hardy when faced with varying water conditions.
Dissolved Oxygen – a minimum of 4mg/L and a max of 10mg/L is required
Temperature – Ideal temperatures are between 18 – 24°C.
Feed – Koi will eat almost anything that is small enough to ingest. They are interesting in that their teeth sit in their throat and not their mouth. Baby Koi need very small foods such as newly hatched brine shrimp, daphnia and infusioria. When they reach adulthood they should feed on high quality pelleted or flaked food.
Growth rate – in ideal conditions koi will grow 3 – 4 inches in length each year.