Yes that little snake needs to be fed hopper to small adult mice. You want the body of their prey to be equal to the widest part of the snakes body. You can find a digital scale on amazon.com for super cheap and they're decent products. And the snake probably was fed fuzzys at petco which are a tad small, but that doesn't mean it was underfed. Those are always a little stressed so they don't eat most of the time.