One of my co-workers kept some in a 55 for a few years. He loved to have them and kept them unheated in his home. The main thing he thought they were good for was to tell him the bluegill's idea of what the season was. When he saw them start to breed in his tank, it was time to go fishing at the lake because they would be up in the shallows at that time. I never did get the details from him on how he cared for them.