White Nile Tilapia

Tilapia serves as a natural biological control for most aquatic plant problems. Tilapia consume floating aquatic plants, such as duckweed water meal, most "undesirable" submerged plants, and most forms of algae. Tilapia rarely compete with other "pond" fish for food. instead, because they consume plants and nutrients unused by other fish species and substantially reduce oxygen-depleting detritus, adding tilapia often increases the population, size and health of other fish. 

Tilapia are commonly used with aquaponics. Aquaponics is a sustainable food production system that combines a traditional aquaculture (raising aquatic animals such as fish in tanks) with hydroponics (cultivating plants in water) in a symbiotic environment. Freshwater fish are the most common aquatic animal raised using aquaponics. In practice, tilapia are the mot popular fish for home and commercial projects that are intended to raise edible fish.