This article would explain your problem...
http://www.saltwatersuccess.com/Clown-trigger-the-trained-dog-in-a-saltwater-tank.html
They are like dogs I tell you! lol
LOL... I was just reading an article on crabs, would of helped you out if I had joined the forum earlier... Here's the link anyway, make sure you ask your aquarium guy before hand if he's any good ;-)...
