Lake Kutubu Rainbow Disease?

[M204]

I have a 55 gallon with 10 lake kutubu rainbows 3 males and the rest female. They are with a brown knife , pecock eel and bristle nose pleco Recently some of my rainbows have gotten white lips. As I examined it closly it doesn't realy look fungusy but almost like dead skin or a scale peeling off but I know this isn't normal, I watched the white lips turn back to blue but then back white. They swim around happy still very colorful always flashing there colors and all stiil eat like fat pigs they have been like this for a week and half now and they haven't changed at all in personality . Does anyone know what this could be? Id apprieciate the help, thanks.

 

[N0body Of The Goat]

This is a common occurance if weekly minimum 50% water changes do not take place in Rainbowfish tanks. Does that apply here?

 

[M204]

I usually do a weekly 50% water change but was a day or two late on the last two water changes do to work scheduale