coral war ?

[cityreefer]

Never have had to really deal with this kind of thing before but i think my corals are firghting wiht each other.
i have a 34gal redsea max been up and running for 3 years
have 2 clown, 6 line, blue cromis.
for corals cabbage leather, toadstool, frogspwan, xenia coral, GSP, and some asst zoos, colt coral

so about 2 weeks ago the colt coral is looking really bad fallin down and changed color from pinkish to a neon green and every one of them in the tank look like they are dieing?

is this the corals fighting wiht eachother or is this someting else, i have had the corals in the tank together for over a year.

anyhelp would be great.