never too late for a fish to learn to hand feed, and never too early. It is easier though when the are young. I hold the food in my fingers and let it dangle. If the fish are brave enough to bite, so be it. If not, I drop the food and keep my hand in the tank. eventually, all of them become brave enough to snatch food out of my fingers. Then I hold the food in my hand, and sort of form a cage around it with my fingers. That way, for the fish to get the food it must swim into my hand. This makes them more comfortable with my hand, and sometimes even let me touch them.