Cage culture of Mozambique tilapia, Oreochromis mossambicus without artificial feeding in maturation ponds of the Phuthaditjhaba sewage system

Difficulties in the use of maturation ponds for conventional fish farming are discussed. A study involving the culture of Oreochromis mossambicus in cages, to prevent predation and to facilitate harvesting is reported. Culture was carried out in the final maturation pond of the Phuthaditjhaba sewage system from October 1981 to March 1982. Water temperatures were suitable for culture of tilapia for about 120 days per annum. The fish grew well except during a month following the overloading of the sewage system. Plankton was generally available and of the right composition. During normal operation water quality, in terms of ammonia nitrogen, nitrite and nitrate nitrogen, phosphate phosphorus and COD , improved.