To establish the growth performance and physiological responses after short-term crowding stress, three Nile tilapia () 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 growth rate, and the growth of New GIFT tilapia ranked second; however, no significant difference was observed between the two strains. The growth rate of Egypt Nile tilapia was the slowest. Viscerosomatic indices of GIFT tilapia and New GIFT tilapia were significantly higher than those of the Egypt Nile tilapia. There was no significant difference in the condition factor among the three groups. At the end of the feeding trial, 40 fish per bucket were exposed to crowding stress (100g/L) for 48h, The effects of a short-term exposure on the physiological responses of fish were determined before stress (0h) and at 6, 12, 24 or 48 h post-crowding. The serum total protein, glucose, glutamic-oxaloacetic transaminase (AST), cholesterol, lysozyme (LSZ) level and hepatic Hsp70mRNA levels in GIFT tilapia and New GIFT tilapia initially increased and then decreased over48 h of crowding stress. Compared with the level at 0 h, the serum cortisol level of the Egypt Nile tilapia was not significantly difference at 48 h post-stress, but the levels in GIFT tilapia and New GIFT tilapia were significantly higher than at 0h. The serum LSZ activity and HSP70 mRNA levels of the Egypt Nile tilapia at 48 h were significantly higher than at 0 h. Overall, the results indicated that short term, high density crowding enhanced the use of serum glucose and triglyceride, but caused liver damage in tilapia. The ability of the Egypt Nile tilapia to resist high density stress is stronger than that of the GIFT tilapia and New GIFT tilapia. Therefore, for intensive culture farming, tilapia should have a reasonable stocking density and less human interference, which will reduce stress responses and healthy breeding of tilapia.