Assorted Reef Hermit CrabsHow to Care for Assorted Reef Hermit Crabs written by Dave Burr Reef Hermit Crabs are superb algae eaters, they will even eat filamentous algae and cyanobacteria. It is very useful in keeping reef aquariums clean and free of undesirable algae. Growth: As Reef Hermit Crabs grow they will need larger shells to take the place of the shells they outgrow. Place several old snail shells in the aquarium where the Reef Hermit Crabs can get to them when the