Corydora can’t stay down

[toothgrinder]

Bronze Cory cat looks kind of bloated mostly on one side, and cannot stay at the bottom. It’s currently trying to wedge itself on moss and stuff to stay near the sand. Tank is 75 gallons been running for over a year and a half and has a lot of corydora and some dojo loaches. No indications from the water or any other fish, just this one Cory out of like 40. Any thoughts? 
 

He’s hiding in moss and I just noticed today after work so I don’t have a picture yet. 

[nabokovfan87]

put him into a breeder box and try to let him recover.  It could be a swim bladder issue and moving him to the top of the water would alleviate some of the stress as well as the pressure that's keeping him from being able to swim. 

As far as treatment, depending what the issue itself is, you're going to have a few different methods that people deal with stuff.

It's difficult because you're looking at some sort of internal damage.