I notice that I have a black crab with red eyes in my 100G that I need to catch. I also have 4 cleaner shrimp in the tank. How do I catch the red eye crab with out catching the shrimp? I put some food in a glass. The glass has a long neck so the crab will not be able to get out. However, the shrimp where in the glass not the crab. The crab is in a hole in a base rock. It would be tough to pull out the rock. Any ideals?