Firemouth no colour

[Rick147]

I had a pair (I think) of firemouths. The male was really harassing the female and bullying her.

I removed the male to a spare tank.

Since then the female has gone really white, no colour at all?

 

[GaryE]

That's normal. They communicate via colours, and she has nothing to say right now. She's unhappy. It's not because he's gone, but because she is a social fish and her own species isn't present. In time, she'll relax and get over the fear caused by the other fish. Maybe then, she'll get some colour.
If she is a he, then the colours are turned off because he doesn't want to attract any more attention. Showing colour is challenging the alpha.