Sally Lightfoot CrabHow to Care for Sally Lightfoot Crab written by Dave Burr The Sally Lightfoot Crab is a superb algae eater. It is very useful in keeping reef aquariums clean and free of undesirable algae. Behavior: Large specimens can be harmful to small fish and invertebrates although this is less likely if there is sufficient algae for the crab to eat. Feeding: If no algae is present in the aquarium you may supplement the Sally Lightfoot Crab's diet with live macro