Does any have some good tips for keeping acanthurus tangs alive because whenever I buy an acanthurus tang they always die either within 1 week to one month. Ive had 2 mimic tangs die,lavender tang just now my new lieutenant all die. The only time I had success was with a 1 inch hippo I've had her for 2 months now and is in perfect health. So I really need to know what I'm doing wrong. Because I never failed with any other species of tang just acanthurus