I've got another 75 gallon tank and was going to set it up as a rift lake tank. However I went to the LFS and was intrigued with the idea of a native North American species tank (bluegills, perch, etc.). While they don't have the colors the africans do, I think it might be kind of a different look. Would I even need a heater for these fish? I assume since they live in colder water they'd be fine without heat.