It's been two and a half months since I stocked my tank. Some of the fish have grown noticeably, while others seem not to have grown at all. It's the same for all three species. The little ones seem healthy. They eat, they swim, they have good color, they behave normally... they just aren't growing! Is this normal? Is it a dominance thing? Should I be worried? Is there anything I can do (short of putting them in a separate tank) to help them grow? I only feed once a day, because I'm very afraid of overfeeding and causing bloat.