Worms it is. Toprfish are a Polypterid, and loke all their cousins relish frozen bloodworms, live blackworms, live earthworms, bits of shrimp (frozen/fresh, preferably raw), and small fishes....my tank of 6 ropes go nuts for live worms.
G. A. Christian Bilou, Herpetologist
Founder/Director, Reptile Rescue Alberta
Past-President, Calgary Aquarium Society