id lower the water level to just a few inches so the frt can go up for air a lot easier. feed him bloodworms. thats what i started with my frt. for pellets, try floating reptomin. worked for me! i would avoid algae discs since they get ripped up too easy. small pnts cant eat the discs too well either.
add salt to the water and raise temp to 83? im no expert with frts but thats what id do. if that doesnt work, maybe take him to the vet. i guess they can get swim bladder problem as well.