I know you say, 4-6 and I plan to 4-6 but can they be of different colors, and/or sizes? I have a LFS who breeds and raises discus, but he keeps the snowwhites with the snow whites,marbros with marbros, etc etc and they all cost different prices, 4-6 juvies that are 3-4 inches would work best right, and I have fish that doesn't go with discus I'm selling them to a guy today, and plan only to keep the cory cats,gold nugget,and clown plecos. I have a 135.