Provide them with insects two to three times a week. Seek the coolest temperature you can find and you can keep frogs for an extended time. My minnow bucket with a spring loaded door makes an ideal container when I go fishing. The bucket is kept half full with water. In this way, the frogs won't get a good footing when they try to hop out as you reach in.
Most people think of smallmouth and largemouth bass when frogs are mentioned as bait.
Believe me, weed walleye and channel cats won't turn down a tasty frog either. Let the frog do the work with some gentle prodding from time to time. A stinger hook can help if fish are continuously striking short. I still can't handle those little fish catchers without a glove but can they catch fish. They aren't limited to walleye, Bass, perch, all panfish, and especially trout just love them.