These include lakes, large reservoirs, farm ponds, rivers, cooling water discharge canals, estuaries and coastal embayments. In the southern U. S., tilapia are among the most suitable fishes for cage culture. The choice of a species for culture depends mainly on availability, legal status, growth rate and cold tolerance.
Many states prohibit the culture of certain species.
Unfor-tunately, T. nilotica, which has the fastest growth rate, is frequently restricted. Hybrids of T. nilotica x Taiwan red tilapia grow as fast as T. nilotica. Hybrids of T. aurea x Florida red tilapia grow at an intermediate rate between Florida and Taiwan red tilapia. Cold tolerance, important in northerly latitudes, is greatest in T. aurea. Tilapia can be cultured at high densities in mesh cages that maintain free circulation of water.