To establish the growth performance and physiological responses after short-term crowding stress, three Nile tilapia(Oreochromis niloticus) strains(GIFT tilapia, new GIFT tilapia and Egypt Nile tilapia) were compared in terms of certain body indices. At day 100 of the experiment, tilapias in the experimental group were exposed to short-term crowding stress to evaluate the serum biochemical parameters and liver HSP70 mRNA expression before and after stress. The results showed that GIFT tilapia had the best g...