I've had 8 in my Reefer 450 since I set my tank up back in October. All have done fine and are very fat and healthy. I feed my fish twice a day. I have heard of people saying you have to buy a bunch at a time to basically plan on 2-3 not making it, but I've never had this problem, I've had Chromis in every tank I've ever had, great schooling fish.