Hi, have you tried feeding him cooked shelled peas?
Also usual ? ammonia, nitrIte and nitrAte please?
Epsom salt baths can be good, but I dont know the ratios to use.
Hmmm doesnt look good, how long has he been like that?
Could be internal bacterial infection, do you have any meds?
I think it may be bloat, in which case a salt bath would be a very good idea. The ratio for salt to water is 1 tablespoon of salt per gallon of water, 20 minutes is usually sufficient.