Aww, he's coloring up nice! You know what it looks like to me, is his tail is paralyzed...gee I hope I'm wrong. But if that is the case, nothing is stopping him from havinh a good life anyways!
Are you sure that bowl is a half gallon? It looks like a 1 gallon to me. But wow, what a strong boy! Keep it up, bettamomma!