I have a Blue Neon goby that's been in my tank for 2.5 years and I have know idea what has caused his stomach to swell up. This started after I did a major overhaul on my 24gal tank. His stomach keeps getting bigger by the day and he's very lethargic with fast breathing. He's still slowly eating, but he's been like this for the last two weeks. Any help would be appreciated.