Mine never eats anything but wood. He does eat a lot of it though. I can watch him gnaw on the driftwood and constantly drop strings of crap. He really makes a mess of the tank he's in but he's too pretty to get rid of.
I wouldn't feed him meaty foods,they can cause digestive problems. But if you do peas are suppose to help with digestion so I would be sure to feed him peas. Mine like cucumber alot so I would give that a try also.