Tilapia are herbivorous fish that feed mainly on algae, aquatic plant cells and almost any plant-based food source. When produced for the food market through aquaculture, their diet may also include standard farm feed products containing fish meal or fish oil. One of the top 10 fish consumed in the United States, tilapia have become the third-most commonly harvested farm fish.
Because of the reduced cost of tilapia farming, this fish has been referred to as the "aquatic chicken" of the trade. Since they are not carnivorous, they are relatively free of the concentrations of toxins that can accumulate at the food chain's higher levels. Representing a good source of protein, farmed tilapia production has reached a revenue level close to that of trout and salmon. The estimated annual value of the farmed tilapia production is $1.8 billion. Most of the fisheries were originally in Africa, but the largest worldwide producer is now China with Egypt in second place.
Since lower levels of omega-3 fats along with a higher ratio of omega-6 fats have been found in tilapia farmed in the U.S., some controversy occurred regarding the fish's status as a healthy food. Studies have been conducted which indicate that the inclusion of flaxseed derivatives, which are a vegetable source of omega-3 fatty acids, into the farmed tilapia diet can help to address nutritional concerns.
Because tilapia feed on troublesome floating aquatic plant life, such as duckweed and algae, they are gaining popularity as a natural form of biological control for aquatic plant problems. Their introduction into an aquatic environment can reduce or eliminate the need for toxic chemicals and algaecides containing heavy metals. The reduction of plant-based aquatic detritus by tilapia contributes to the size and health of the other fish.