Rescued injured toad...?

This is not my first frog/toad, just my first one this size as I have had an american bullfrog before that was as big as a small plate.

I rescued this frog on the 3rd day that he found me...long but cute story. He is missing 75% of his back leg, but appears and acts like he is healthy, and it seems to be healing well.

My question is, aside from giving him (yes I'm sure its a him) the comforts of "home" in his aquarium...what should I feed one this small (1.75" from nose to rear)? Crickets from bait shops is what I fed my bullfrog, but they are huge and I can't see how this frog would be able to eat them. I've read earthworms, meal worms, crickets, etc...but he seems to have no interest in the crickets, or mealworms, although I think he did eat the earthworm that I put in there...he's looking really fat today, lol.

Anyone have suggestions? I'm open to anything as I plan on keeping him long term.