Help !! Dommino not doing well

[Captainhemo]

Hi
I just got in and one of y domminos has totally lost a ll his black color pretty much. She is swiimming very eratically , darting all over the place. her eyes appear to look normal and there is no notiicable parasites rr anything else on her.
She was fine when I left earlier this evening, she ate well today , nothing out of the ordinary. Just all the sudden she seems to have lost most of her blacm coloration and is swimming / darting very irratically
I have a 2nd Dommino in the same tank and so far he is not , or doesnt seem to be affected

Anyone have any ideas on what may be weron with her and what I can do to help ?

Any help would be really apprciated

captainhemo