When the rock crabs get big enough, they will take out pretty large fish. I have seen it right in front of my eyes, a black rock crab was hiding in the rock, the a huge pincer whipped out and grabbed a sizable fish (cant remember which one right now), about 3" long, and it was dead.
This was at Aquarium Illusions in their large display tank, they had no idea they had a rock crab until they saw the aftermath.
Maybe not all rock crabs get this big or agressive though, but if you can remove them, I would.
|