I have a friend who keeps a, I believe it is, 60 gallon tank. He has a huge goldfish in it that he won from the fair several years ago, and he would like to have some other fish in there but his goldfish eats them all. The goldfish has eaten other goldfish and a small pleco. Any other fish would have to be pretty hardy, I'm not sure about the level of care involved in his tank. He changes the water with a hose and some water conditioner, and for a lid he has a large board of wood. Anyone have any suggestions on large, cheapish fish that could accompany a goldfish?