Funny thing is the little guy didn't hide in the rocks I provided, just went to a corner, so I think the discoloration was just stress, that's what the LFS
said. Anyway, last night I exchanged the little one for the largest one they had (same size as the largest I had originally). So I started with a big one, a slightly smaller one, and a small one. As I write this, the original big bully and the other one are picking on the new one, but he is holding his ground pretty well, doing a tail wag at them. I hope it works out now. I guess they list this as a beginner's fish because they are cheap and hardy, but beginners don't want to see fish harassed to death! lol My goal is to not have a single fish death but I know that's unrealistic.