A lot of BGK's can be hand fed. If you try holding food at the entrance to his cave he might take it from your hand. If not, dont bother, but if it does, keep doing it and it might come out further after a while and end up coming up to the top when you feed. It might not, especially if there are other fish in there that its a bit wary of, but its definitely possible, especially when the tank lights are off. My current one comes straight out the second the tank light goes off. I've had a few in the past that were hand fed.
Just get a good look at him every now and then to make sure he's not wasting away. They'll also eat things like sinking pellets, massivore, prawns, cockles, etc.