Weather (Dojo) Loach health concern

[tmcmullen]

I've had my weather loach for about 8 or 9 years now. Lately he is acting a little funny - laying on top of the out-take system for my pump, suddenly darting to the top for air. He is normally very mild and not very active. I noticed that he has a swollen abdomen about 3/4 down his body (from his head). Does anyone have any idea what that could be from? He is in a 55 Gal with recently changed water and filtration. He started acting this way before I cleaned the tank. His behavior prompted me to clean the tank.

Thanks for any help you can provide!

[Diana]

Could he be constipated?