The giant freshwater prawn, Macrobrachium rosenbergii, is one of the most important crustaceans cultured commercially in mainland China and other Pacific Rim countries. In recent years, chemical treatment for maintaining optimal water quality has gained attention because farmers use antiviral and antibacterial chemicals to prevent vibriosis and several diseases. Copper sulfate is one of the chemicals that are commonly applied to shrimp ponds to eradicate filamentous algae. The application of copper sulfate in ponds is also very effective in reducing the abundance of Microcystis and other blue-green algae. The application rate of copper sulfate varies from 0.025 to 2 mg/1 and is directly related to total alkalinity. However, farmers often use an excess amount of copper sulfate in shrimp pond management. As a result, the growth and survival rate of animals decrease significantly, and accordingly, the pond management cost tends to increase year by year. As Cu²⁺ pollution can be a potential limiting factor to the crustacean culture, studies on its influence on M. roenbergii are of great significance in establishing scientific methods for safe aquaculture.Copper (Cu²⁺) is one of the most important nutrient elements in crustaceans, which is essential to the production of hemocyanin. It also plays indispensable roles in a large number of enzymes when they are functioning. Crustacean tissues are able to accumulate copper in accordance with the external copper concentrations. However, if an excess dose of copper is used, the toxicity of copper also has significant implications for the affected proteins that require copper proteins as an integral part of their structures. This toxicity is reflected at the molecular, cellular, and tissue levels in , affected individuals. Presently, there are several reports on the mechanism of the toxic effects of water-borne copper on crustaceans, but they are mainly related to the evaluation of LC50. Therefore, there is a paucity of information concerning copper-induced damages in the principal tissues of the giant freshwater prawn M rosenbergii.In our present study, the juvenile giant freshwater prawn M. rosenbergii was selected as experimental animals and the effects of water-borne copper on M. rosenbergii have been conducted by use of morphologic, physiologic, biochemical, methods. Meanwhile, electric microscopic, biochemical enzymes and trace element analysis were also used for measurement. Our study aims at clarifying the mechanism of toxic effects of copper on M. rosenbergii and our results are bound to have both