This study investigated the effects of industrial wastes of a paper mill on fish. Chemical analyses were made of the effluent and of the river water before it entered the mill and at the effluent entry point. Static bioassay techniques were used to determine tolerances to the effluent of ten fish species which were abundant in the paper mill area. Fish were collected from the effluent entry point into the river. An abundant fish fauna was found. Charmin Paper Products Company, Cheboygan, Michigan, treats its waste products thoroughly and is an example of what an industry can do to reduce water pollution. The common shiner, Notropis cornutus, was found to be intolerant to even low concentrations of the effluent. Thus, its presence in an area would indicate a very low level of pollution of this type.