I have lost 6 chromis now total so I feel your pain. I have also done a lot of research, these fish are often caught with cyanide, as mentioned previously and handled roughly. If you do a google search on chromis there are many, many stories of people buying a school only to have them slowly die, one at a time in their tanks, either from bullying or their rough capture. Cyanide poisoning ruins them and while they will eat and eat they cannot get nutrients so they starve, oftentimes you can see discolorations and problems begin with their bodies as they "break down." I think many are having poor luck with them recently.