fish discolored

[mteeitup]

My fish seem discolored, I have a yellow og puffer, brown tang.triger and a black danzel, The black danzel is now gray, the puffer is getting white the tang is getting gray bloches and the triger colers are not as brite, can you tell me what is going on, also the trigers eyes might be hazey, but all seem to be doing very well active and eat well.

 

[mteeitup]

i have a 55 gal. corner tank, my test all nitrite levels are at 0, ammonia is at 0, the ph is low it is at 7.6 I have a wet dry filter system, uv sterilizer and a porten skimmer all the equipment is over kill. the fish size are the puffer is about 6" long, the tang is 3" , the trigger is 2.5" and the danzel is 1.5". i feed them live fish and frozen brine shrimp.
thanks