clowns problem

[KMACAS]

I have a 50 gallon tank that has been going for two months In it I have 6 percula clowns. three days ago I have added 12 more clowns and three have died and the water is geting fogy .I have moved 5 clowns in a nother tank and I am left with 9 in the tank with problems.I have also added a yellow botom Anemone at the same time as the clowns. Amonia is alitle bit up but not to bad 0.50 everything els is good.please can some one hepl me so the other clowns do not die.
thank you