I have a 150 gallon reef tank with 2 Skunk Cleaners, 2 firefish and 1 watchman goby. I have had these fish for about 3 months. I have tried to add 2 Royal Grammas, 1 Blackcap & 2 Powder Blue Tangs (not at the same time). They have all died from Ick. Water conditions are well within the 'norms'...