My betta is lurking at the bottom of our tank, he looks like he's having trouble breathing, gasping for breath...his colour looks good, i noticed he was looking off last night and first thing this morning i thought he'd had it...he seems to have a bloated belly too, I've got another spare tank set up..do I move him or will that stress him out? He's gettin on a bit, about 18months - 2 years old...do I leave him in peace or do something?!?