This paper is a review on modelling the effects of water pollution and eutrophication on the survival or extinction of aquatic species. The models are formulated using the system of non-linear ordinary differential equations. The systems are modelled in consideration of the variables like concentration of dissolved oxygen(DO), concentration of acid and metal, density of resources(phytoplankton), nutrient concentration and density of fish population. Using stability analysis and numerical simulation the conditions for the existence of equilibrium points have been drawn. And the criteria for the survival or extinction of the aquatic species have been obtain.

Keywords : Mathematical Modelling, Eutrophication, Dissolved Oxygen(DO), Nutrients.