I got my half moon, a couple of days ago, he looked very vibrant and active at the store, but today we noticed him not being able to swim very well. It looks as though his bum sinks (back half, tail area). That was in the morning. When I came home from school, he was floating on his side and still having trouble swimming, his find seem to be shrinking and sticking together and his color is a lot duller. He was very bright blue but now he is a light reddish/purple color! I need help!!