So we got a new male betta today, a double tail. Well he looked fine and was swimming around fine in his cup but when we got him home and put him in his new tank I noticed something didn't look right. His lower body (codual fin area) looks bloated and his dorsal fin is starting to curl at the tips. He also just wants to chill at the surface, and when he does swim towards the bottom it takes quite a bit of effort and he just floats right back up as soon as he stops struggling. (hes only in a one gallon) I'm not sure whats wrong with him. Here are a few pictures to show what I mean. They aren't great, but its something.
Struggling to get towards the bottom:
Chilling at the surface:
If you look closly you can kinda see his weird bloat-y-ness, Its the best picture I could get