Okay so this isnt the first time this happened. Second infact. My fish Sparta a red and white CT can't seem to stay at the bottom of the tank. He just floats right back up to the top and kinda "lays" on his side. I haven't changed anything in the tank between these two times this has happened (only a few days apart.) and my other fish is fine (They share a divided 10 g). I haven't fed him yet today as I usually feed them around 10:30pm Central Pacific Time as that is what time I go to bed amd it is part of my nightly routine.
What could be causing this?
How do I fix it?
I don't have a 2nd Hospital Tank.