Unfortunately, I don't think this bulge in his abdomen is just from eating a lot. He has been swimming lately some of the time in a sort of nose-up position, say 30-45 degrees, but he can still point down to eat or whatever he needs to do. Today I've noticed he spends some time resting on the bottom or on rocks, like swimming is tiring, although he still spends more time swimming than resting. The bulge looks pretty much the same on both sides. Any ideas?