My clownfish just recently started rubbing on my live rock or anything it can like the powerhead or the heater. I have heard of rubbing before but i don't know what causes it. What should i look for or do to stop the problem? It's not really bad right now. I just noticed yesterday and i just have to catch her in the act because she doesn't do it very often but when she does she goes crazy. Thanks for any advice you can give me.