Melanosis in bass is caused by an overproduction of melanin, the pigment responsible for dark coloration in animals. Melanosis is more common in certain species of bass, such as largemouth and smallmouth bass. The condition is not harmful to the fish and does not require any medical intervention. There is no known treatment for melanosis and scientists do not know what causes it. It is not contagious and cannot be transmitted to other fish. Personally I think it looks really cool on fish and the