Like most North American ranids, leopard frogs are voracious, (if it moves and fits in their mouth, it's history). My bullfrogs relish large feeder goldfish. You can try small feeders with your leo's. If your using a water dish or bowl, make sure it's deep enough and only introduce a small number. Try small crayfish, too. These make up part of their diet in the wild. Minnows from bait shops don't survive for long so goldfish are a better species for feeding purposes but try not to offer them to frequently. Variety is excellent for all critters. Heck, I love pasta but I wouldn't want it everyday!