This is a "Bad" that you get with live rock. And, of course we have them. How do we know? Well we are down to 1 Banggai Cardinal now. Slowly they have died off just like the clowns did. Ken and Linny replaced the 1 twice...so have lost 5 fish and now it looks as though the last one will die too. They attach themselves to the fish, suck blood and cause the fish a slow death. What does it mean for our tank? DISASTER! The plan of attack is either bad or badder. (nice grammar) NO really our choice now is to A) remove the entire sand bed, keep our live rock as is and have no fish for 8-12 months to hopefully eradicate this pest or B) throw away all live rock, live sand and start again. We would reset up the tank after a very thorough cleaning and place a small substrate layer, new live rock from Ken and Linny and aged water from them to put all animals back into the tank with.....what would you do? Either way we are wasting and/or re-investing several hundred dollars. Leaves a bad taste in your mouth....