Crab Id

[Beverly]

Marcus,

Is the coralline algae being eaten around the holes? If so, that's probably all it's eating, though it may snack on stray foods you feed your fish.

I'm guessing that you found this crab after lights out while flashlighting the tank. If so, the best say to observe this crab is to shine the brightest part of the light near but not on the crab so only dull light is on it. Have a look at what it's eating then and let us know what you discover.