Three months feeding study periods were conducted to evaluate the efficacy of SP as a chemoprotective agent in cultured O.niloticus. The pre-acclimated fish were divided into 6 equal groups. Group 1 was fed on a basal diet (control) and the other groups were dietary supplemented with a single graded concentration of dried SP at 5, 7.5, 10, 15, and 20 g kg1 diet fed,respectively. At the end of each month, the P53 expression level relative to control was estimated in liver of experimental groups.