Sounds about right. I usually have a 4-6" one in a 5g glass jar but they get replaced every couple weeks, I put them back where I got them and get another. They go back fat and confused. I really like them, they got attitude.GTS said:You could consider them north american convicts however male bluegill can get 8"+ and weigh in at a pound. So I would say a 55 gallon tank is minimum for one. The extra swiming room in the 55 gallon would make a big difference IMO.
You could keep a redbreast sunfish in a 29 gallon for life. However bluegill,redear,warmouth etc need atleast a 55 gallon.