shrinking fins

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...

Ok so I posted this problem recently before but it did not get answered so here goes again. My delta tail male, Spud, has a problem. I think his fins are shrinking! They are a tinge of red at the tips and there is a clean peice missing. It looks like it has regrowth (clear fins), but it has been...