Most of the studies conducted on temperature tolerance of tilapia suggested an ‘optimum temperature
range’ for the maximum performance of these fish.
This range is about 24-32 1C, depending on the fish
species and size. For example, Nile tilapia maintain
their optimum performance at 27-30 1C (Beamish,1970) and 28^32 1C (El Gamal1988). Mozambique tilapia (O re o chromi s m ossam bi cu s) maintain their optimum growth also at 28^30 1C (Pauly 1976). The
present study demonstrated that rearing Nile tilapia
fry at the optimum water temperature (28 1C), lying
within their optimum temperature range, has resulted
ina signi¢cant improvement intheir performance and
survival. Meanwhile, fish growth rates and feed utili-zation effciency were significantly reduced at 24 (lower suboptimal) and 32 1C (upper suboptimal).