Something Up With My Molly?

[phantomlink]

awhile ago I bought two Dalmation Lyretail Mollies, and the male seems... odd. His chest is growing and I have no idea why or what it could be. His scales are fine the only change he's done is instead of swimming around everywhere he just kinda swims against the current and doesnt move much

Any idea whats up?

 

[kayisnew]

Could be swim bladder disease, have you checked your tank parameters recently?

 

[phantomlink]

Yup and they're fine, ammonia, nitrate, and nitrite are all 0 and all the other fish ( see 20 gallon in my sig ) are fine