Hi, we have a 130 gallon established tank. We have had it for about 2 years now. We do have a weekly maintenance crew for the tank that handles dosing, cleaning, water changes, etc. Recently we purchased 2 tangs and a fox face from the company that performs our maintenance. They were to be quarantined with the purchaser for 2 weeks before being introduced to our tank. The new fish were brought a week later during maintenance and added to our tank. We had issues with our Domino Damsels when the new fish were introduced, we basically dismantled all of the live rock to catch the 2 problem domino damsels. Within two days the new Tangs and Fox Face died. Most of our existing fish including our clowns, mandarins, tangs, devil damsel, dottyback, pretty much everything began with what we thought was Ich, but appears more so now that we had Marine Velvet. Everything has died except Hippo tang and a six line wrasse. We are devastated. Our maintenance crew advised we caused the disease by stirring up the sand bed when catching the original Domino Damsels. Is it possible that we did cause the disease to wipe out our tank by moving the rock and stirring the bed when rock was moved?