Dietary protein for reaching better growing Oreochromis niloticus including gradual protein levels, taking into account that optimum protein levels for grown fish will help to reduce the impact of ammonia on fish health. Herein, this study verified a theory which assumes ammonia induces changes in fish tissues responsible for ammonia excretion by a mechanism coupled to capillary endothelial cells. Fish feeding on a higher level of protein caused expression of MMP markers. Alongside, ammonia raised the activity of interstitial matrix metalloproteinases MMP-9. The rise of cell permeability maybe amended via using of an inhibitor of MMP. The results support an idea that stimulation of MMPs in brain endothelial cells contributes to the variations in permeability and cerebral vasogenic component, renal and gill tissues associated with ammonia implication. Detailed considerate of the response to ammonia stress and tolerance in tilapia can provide useful information for fish breeding professionals to expand aquaculture.