clownfish bloat

LAtely one of my clowns has been doing a float then he will swim normal and float to top as picture shows I have taken some pictures and posted, he has done flips before which Im thinking is a clown thing but this I dont know I mean there are other fish in my tank, none have signs of anything bad. Its almost like bloat that comes and goes, any thoughts on this? Ive had him for mabe 8mths, and the rest of my fish in that tank
between 3 and 6 months
Im editing just to say the other clown is now doing the sideways float. I forgot to mentune they are both piglets and love to eat. I feed rotifers, other frozen food, seaweed, pellets, flakes water testing is fine but gonna test again tomorrow. I do have to add water every couple days as we have a wood stove so evaporation, All other fish are fine

In searching the web I found this; it might help.

As for the bloating, try dosing the tank with Epsom salts: 1 tablespoon/5 gallons of water. That should help the bloating, it will take a few days to happen. If that doesn't work, try feeding them a medicated flake. Watch for signs of possible internal parasites, if the bloated areas are moving, or their feces has thread like worms in it. If that's the case, there are anti-parasitic flakes as well. I would recommend moving them to QT to treat them.

clndisNutr

Is the epson salts safe for everything else? They have all been together and the tank hasnt had anything added I dont have another tank to put him in. Could it have to do with eating fast and getting in air? even when I try to get the food down from the top of the tank (ive been trying to get it all to sink right away) he goes to the top to eat then the wierd behavior happens

You should use frozen food. If you are using flakes and pellet foods, those can lead to algae problems. I doubt it's from him ingesting air, but the epsom salts won't hurt the other things in your tank.