why does my khuli loach change color

[MARITA]

I have noticed that my khuli loach seems to change color lately. He changes from strong colors to a greyish looking color from one day to another. What does it mean when they go from normal color to this light greyish color and then back to normal again???

[LoachOrgy]

it may be greying out.

mine do this when they eat. i am not exactly sure what it means.