I feed my White's in a container seperate from his tank. In like a 6 x 4 tupperware dish. Ill put him in there(he knows what this means by now) and just put the food in with him,when he sees it wiggling around,hell go for it,or he should atleast. I've gotten my White's to eat a pinkie, but I'd only do it once every 3 months or so, because it only took the one to make him overweight.Do this at night, when the frog is already awake, dont worry the pinkie will squirm around. Same for nightcrawlers,just put them in with him,(only one or two-theyre fatty) he should go for them. If he isnt eating and is getting skinny,even if you offer him food, maybe he just cant find it or has something wrong with him.If hes really active at night,it can be okay. Does he do regular things like soak and sit in a usual spot? Or does he try to escape?good luck.