In intensive culture, the two species of brackish water tilapia, T. guineensis and S. melanotheron, have proved disappointing. Even under most favourable conditions, i. e. the monosex male culture of S. melanotheron, a poor growth rate (about 0.5 g.d−1) and a mediocre feed conversion do not presage a profitable aquaculture exploitation. On the other hand, extensive culture trials using the original "acadja-enclosure" technique have given very encouraging results. Annual fish yields of more than 8 t/ha, including 70 to 80% of S. melanotheron of marketable size, are possible without any artificial feeding.