bluegills are normally pretty aggrseive fish especially in that small of a tank, Ive always hated seeing those poor goldfish at fairs, you shoukd think about getting a little biger tank, you will be surprised how big they can get, plus the fact that there pooping machines doesnt help, heck i catually seen a good deal at meijers ( i know weird ) It was a 20 gallon tank with everything including hood,lights, filter, net,heater, and food. It was a pretty good deal at i think around $60/$70 and if you were to get an extar filter it would only be $15 extra. ANyways thats my suggestion, thne you would have an emty 10 gallon to put some gourami's, mollies, guppy's, or anything you wish in, all you would have to do is take the heater from the 20 gallon tank (because it comes with a heater and you wouldnt need one for the godfish ). Yeah i sorta rambled on...lol