I've been worried about this same issue. From what I have read, they can overeat. Now if they are in with other fish, I doubt that can happen.
I feed mine frozen blood worms and he'll eat what he can find. They have very bad vision. I usually watch him eat a little and turn off the lights. I doubt he gets much.
Now when I feed him freeze dried brine shrimp and it sits on the top, he'll eat until his tummy starts getting big. He'll float around the top of the tank and eat everything that is sort of stuck to the sides of the tank. I've cut back.
He ignores the flakes.
Do you have yours in with fish?