A true coldwater fish is a fish that cannot be happy in temperatures above 62 degrees. Ie. Sterlet and most sturgeon. Goldfish are a false coldwater fish. Sunfish are a temperate water fish, not a coldwater fish. A temperate water fish is a fish that preferes temperate temperatures between 62-76. A Tropical fish preferes 68-80. THey can live together quite happily if someone is willing to let them adapt.
