Blue leg hermit crabs are the most popular algae grazing hermit that we sell. Our blue leg hermits are not the tiny little black ones that some people sell, but instead are the larger ones that live in shells that are about 3/4 of an inch long. They are very active and will aggressively attack most hair algae and other fleshy algae that live in your tank. These combined with sally lightfoot crabs, emerald crabs, and astrea snails will keep your algae under control. Blue legs are very easy to care for and will eat anything presented to them. They will not attack other invertebrates but is something dies; they will dispose of anything that remains.