I'm a semi-new aquarium keeper and I currently have a 75 gallon freshwater tank. Only fish in it are a Pleco (about 14 inches) and 4 Silver dollars(3 about 4-5 inches, one about 2 1/2 inches). I would like to add a new tank mate; thinking along the lines on an African Butterfly fish. I have a bottom dweller, 4 middle dwellers and thats why I'd like a Surface/top dweller. Would I be overstocking my tank? And, would an African Butterfly fish cooperate with my seemingly quite calm fish? Thanks! ~eric