Last week we spotted the crab in the sump and decided that we would let him be - however, just for the sake of doing it, we placed a small piece of raw meat in a glass, tipped it up against the rock in the sump and by morning we had ourselves a crab!
It's body is about the size of a dime - quite small. After showing the kids we released it back into the wilds of the sump to live a happy productive life.
