No, they don't look like anchorworms to me. For reference, anchorworms are crustaceans, not worms. Where did you get that fish? Try removing it with forceps or tweezers. If it squirms, it is not anchorworm. Stick to praziquantel for now as it works well for most nematodes and other parasites (except for external parasites such as anchorworms that need trichlorfon or dimilin).