Organochlorine pesticides were recommended in Benin in the 1960s (DDT, lindane, dieldrin, heptachlore, etc.) and from 1999 till 2007 (endosulfan) for the control of cotton plant devastators. Since the end of these periods, the illegal use of certain molecules of this family of pesticides has been observed in the cotton basin. Organochlorine molecules are very lipophilic and very persistent and quickly degrade under the effects of ultraviolet rays into by products which are generally more toxic and stabler than the initial compounds. When they are used in fields, they can still be found in the aquatic ecosystems several years later. A literature review showed the state of contamination in different Benin aquatic biotopes by these dangerous products. Indeed, alarming rates of endosulfan, DDT, dieldrin and heptachlor were found in certain waters, such as the waters of the park W. In sediments of Bétérou high levels of DDT, endosulfan and lindane were also revealed. An investigation of tilapia Sarotherodon melanotheron males captured along the Oueme river showed the presence of lindane, dieldrin, heptachlor, and pp'-TDE as well as a high plasmatic concentration of vitellogenin. Alarming rates of DDT, endosulfan, lindane and dieldrin were also found in Polypterus endlicheri captured in the waters of the Pendjari.