I noticed today that my male angelfish is losing his color and must be stressed. I recently adjusted the way that the canister filter splashed the surface so my first thought was that the 02 level in the tank might be getting low so I through an air pump in the tank. They are in a planted tank and I have never had an airstone in the tank to date. While I was doing this though I noticed something odd about my fish. I snapped a couple pictures and if any one has any advice I would appreciate it.

The first picture is of the the other angel fish and it seems to be happening to it as well. The second picture is a close up of the one that seems to be affected the most.