Effect of injection of Oreochromis niloticus (L.) with piscine pituitary extract (PE) of carp and Human Chorionic Gonadotropin (HCG) at two different temperatures (25 and 28° C) was studied. The results revealed that the rise of water temperature enhances the maturation process. Using PE at 28° C lead to the appearance of a high percentages (66.67 %) of ripe females after 20 days, while injection of HCG at the same temperature accelerated the rate of maturity stages and high percentage of stage IV appeared after 40 days. Ova size has been increased reaching ripeness after 20 and 40 days following injection with PE and HCG. The final maturation stage included nuclear migration from central to peripheral position in the oocyte. The gonadosomatic index (GSI) of female fish increased progressively after hormone treatment at higher temperatures. It is obvious that the HCG injection gave better results than PE. In addition, enzymes of the ovary (Aspartate and Alanine aminotransferases - AST and ALT) were also investigated in relation to ovarian development, at two different temperatures (i.e. 25° C and 28° C).