The present study was carried out to investigate the effect of high temperature levels on three species of Nile fish; Tilapia nilotica, labeo nilotica; and Gambosia affinis. The avoidance temperature (AT), critical thermal maximum (CTM), and upper incipient lethal temperature were recorded at three levels of acclimation temperature. The effect of
an haematological picture (Hb, RBCs increased temperature levels count, PCV, MCV, MCH, and MCHC) of Tilapia nilotica fish for one week were investigated.