An extensive cuivivation of the cichlids Tilapia rendalli and its predator Cichla ocellaris was undertaken at a lake in the Ribeirão Preto (State of São Paulo) Campus of the University of São Paulo. Comparison of the results with former ones, obtained before the introduction of the predator, showed a considerable increase of tilapias, both in total length and total weight, showing the advantage of rearing them together.