If you've only had him a month he still might be a bit shy. I'd try just sitting next to him, maybe put your hand in the water and watch him a lot. Get him used to you. If he's consistently eating from the same spot, I'd try holding food in that same spot and see if he takes it from you. Then you might be able to lure him out with food. Or just throw it out a little bit to begin with and avoid the hand idea.
You could always move the hiding spot, but that might just upset him and once he finds it again he just chooses to stay there.
My Asian RTC has been very shy too, he's still small and in an aquarium at the moment. I've jsut been trying to watch him and get as close to him as possible without spooking him. Moreso when he actually comes out of hiding.