hmmm, crabs...ewww j/k. My crabs seem well behaved, haven't killed any snails yet and don't seem to annoy the corals, but I don't have a lot yet.
I agree with the snails, but they are a great with the intial set up until things start to stabilize in the tank. I just added 10 mexican turbos and yes, they knock everything over that isn't glued down - between them and the cleaner shrimp.... But, they've done a great job cleaning up the red turf algae I was dealing with, almost all gone after 2 weeks, think I may have to give a few away so they don't starve, but they still have some work to do!
CUC reefer school...

good one!