Under hatchery conditions Gyrodactylus elegans is one of the principal parasites of the golden shiner. It becomes epizootic in the spring at temperatures of 40 to 60° F. It spreads rapidly and causes pronounced mortality. The operational procedure in shiner hatcheries requires both pond and tank treatment. For pond treatment 25 p.p.m. formalin gives excellent control. In tanks 50 p.p.m. for 14 hours gives satisfactory control.