peer reviewed ; The paper reports on some of the final results of a 6 year ( 1977-1983) research project dealing with the intensive culture of the Nile tilapia, Oreochromis niloticus in the heated effluent of the Tihange nuclear power plant on the River Meuse. It also gives an outline of the commercial tilapia rearing operations by the fish farm Piscimeuse SA on the Tihange site. In experimental male monosex culture, a market size 300-350g tilapia is produced in 8-9 months starling from the egg stage. The commercial development of the research programme took place in 1984 when the fish farm Piscimeuse SA started operating, utilizing the heated effluent at the rate of 1 800m³.h-1. This fish farm rears two species of tilapias (0. niloticus and 0. aureus) and also other warm water fishes such as catfishes ( Clarias lazera, Siluris glanis, and Ictalurus punctatus) , carps ( Cyprinus carpio) and goldfish (Carassius auratus). In 1986, the yield of tilapias amounted to 136t.