I found my cory cat laying on its side during my weekly water change on Sunday. He has red blotches on his side (the whitish looking specs is air bubbles, aerator was too high when i first put in this quarantine tank. I took him out to quarantine and found when he tried to swim he can't upright himself. He just lays on his side or semi upside down. I started treating him with API fin and body. The red blotches have started to go away but he's still just laying on his side and can't swim right if I upright him in a bit he flops and is on his side again. He continues to live and just not sure what else to do or how long it will take or if he'll heal. The other corycats are just fine.
I check water parameters frequently with strip tests or Api master kit and everything is good. I've got this a couple months ago from local pet store.