my guys are kept in the 76-80 range. the slow breath rate is a good thing, as long as he's not gasping. Since fire eels are not true eels the normal "gasping" you see in true eels isn't a normal sign and case w/ these fish. I have noticed they will gasp more then other fish, imo it's because they are use to oxygen rich waters.
live ghost shrimp as you've offered, earthworms, frozen krill and silversides. are all good foods to try. Earthworms are pretty much irresistable to these guys. the Bichirs or RCK may also be bullying it. Turn the lights off for abit. then drop a few worms outside where the eels camped out. once he "sniffs it" if he doesn't take it. Then I would indeed be worried, and worm him. If he takes it 'n spits it.. try smaller peices. took 1 of my fires about 1 week to settle in.. and the other 2 almost a month. Some peopel get them settled and eating right away.