Today I noticed that one of my boys is very bloated. He's got a large bulge in his stomach area. I tried in vain to get a picture, but he wouldn't hold still and the only camera that I have right now (on my phone) sucks. Neither of the other two fish are bloated and none are acting differently.
The tank is a 10g divided with two other fish. It's filtered and heated at 78 degrees. I change about half the water once a week and use API Stress Coat +. I feed them 3 Omega One pellets twice per day and skip a day once a week. I don't know the water parameters.
I'm hoping he will just poop and it will go away, but if I end up having to treat with Epsom salt, is it okay to treat the entire tank or should I take the bloated boy out and treat him alone?