I have a crab in my tank, and a pair of Clownfish that haven't shown any aggression to each other, but the Clownfish have what looks like indents, cuts, or scrapes on them, and wondering if the crab was scratching them. The tank size is a 33 gallon cube, don't know if I should just leave them be, or interfere, but the Clownfish could be scraping themselves on the live rock too, I don't really know