i have a 50 gallon tank with 12 feeder and 2 big goldfish, a betta (hes nice to them. my bf put another one in just to watch them fight!) and another fish which i dont know what it is! its about 3 inches, gray, with black stripes. ive had them all together for a while but what other types of fish can i add? (no more bettas) i want colorful, pretty ones. i want to take out debo (thats the huge goldfish) bcus he knocks everything down and maybe put betta boo in with him. bb leaves debo alone!