What is tilapia?
The common name tilapia covers almost a hundred species of chiclids belonging to Tilapiini, a tribe within the family Cichlidae. Many species, hybrids and variants of tilapia fish are easy to raise in captivity and they are a common choice for ponds and aquaponics where fish is raised to become food for humans.
In the wild, tilapia is chiefly found in freshwater, but some live in brackish conditions. Tilapia inhabit everything from lakes and rivers to ponds and shallow streams, and it is not difficult to understand why they easily adapt to life in artificial ponds and aquaponic set ups.
Data from the 21st century show that tilapia is the fourth-most consumed fish by humans in the United States. The fish has a mild taste and is easy to cook.
Unless conditions are very poor, you can expect tilapia to grow from fingerling stage to 1.5 lbs within a year. At 1.5 lbs they will do well as food.
Let the tilapia provide your plants with nutrients
In a conventional hydroponic set up, you must provide your plants with a properly balance nutrient liquid. In an aquaponic set up with tilapia, you feed the fish and the fish provide nutrients for the plants. It’s a more natural system that mimics how things work out in the wild.
Since your set up mimics a natural system, you will not be cleaning out the nutrient solution and replacing it with new one. You will replace water that has evaporated, and once in while you will do a partial water change to keep the fish happy, just as you would in an aquarium. The plants absorb compounds that are dangerous to fish and use these compounds as food, helping to keep the water suitable for the fish to live in.
It is important not to overfeed the fish, because overfed fish will produce more waste than the plants can absorb. Also, leftover uneaten food in the water will convert to harmful compounds. If you suspect that you might have overfeed the set up and the fish are suffering, simply stop feeding them for 48 hours and do a few small partial water changes over the course of three days. Several partial water changes is better than one big chock to the system.
Example set sup
Which size and ratio that is ideal depends on various factors, and you should be ready to adjust the situation in your aquaponics to find the ideal balance.
If you are a beginner with a 60 gallon tank, and seven to eight square feet of growing space, roughly ten tilapia is a good start. This will be enough for seven or so tomato plants.
A pump will be necessary to move the water around and make sure there is enough oxygen in it. Calculate roughly 15 watts of power for the pump. You can get a suitable one in an aquarium store, you don’t have to go out and by a special “aquaponics pump”.
Feeding the fish
To feed 10 tilapia for a year, and raise them from fingerling stage to suitable eating size, you will need around 230 lbs of fish food (23 lbs per fish and year). The exact number will depend on the quality of the food.
Tilapia and live on a wide range of food types, so put some effort into finding out which affordable alternatives that are available where you live. Wild tilapia feed chiefly on algae.
Many people shy away from eating tilapia since they have heard horror stories about large-scale farms where tilapia is raised in rather appalling conditions.
With your own aquaponics set up, you are in charge of the system, so you can make sure that the tilapia is raised in a way that makes you want to eat them. For instance, you are fully in control of which food to give the fish. If you want to feed them organic grains or waste products from an organics farm, that is absolutely doable. Tilapia eat algae in the wild and will happily munch down a wide range of plant material. They love duckweed since that is so rich in proteins.