Need help keeping new fish alive.

[hummer]

Thanks for the replies. I watch them eat all the time and they seem to be getting enough food. They are a lot faster than the other fish. I don't see anyone pick on them. They are bigger than all the other fish except the blue tang which is about the same size.
The blue tang was the last fish I got that has survived. I got him 3 years ago. 9 months ago I bought a new 90Gal w/ 33Gal sump. Previously i had a 77Gal.
Live Rock: 50-60lbs.
Skimmer: Euro-Reef RS100
Phosban reactor with carbon.
The system never had Ick or any other disease. Except the blue tang has lateral line.
pH: 8.2
Ammonia: 0.05
Nitrate: 0
Nitrite: 0
Calcium: 400
Magnesium: 1305
Alkalinity: 177
KH: 4.9
Salinity: 1.025
Temp: 25-26 celcius
Fish that have died in the last 3 years within 1 month of getting them (purchased from 3 different fish stores):
2 watchman golby, 5 blue/green chromis, 3 firefish, blenny, raccoon butterfly, threadfin butterfly, salfin tang and a rabbitfish.