IME, fish poo is usually the colour of whatever they've eaten. I know when it's a different pellet than their staple, it looks a different colour. BW look different too.
Just keep watching his poo, if it turns white you might have trouble with parasites. If after a few days when it's safe to feed him again, watch his poo then.
So fun, these fish. Oh! and metro (long word, just starts with metro) is good for parasites. IT can be added to food or (at least the kind I have) can be dissolved in water. Don't start metro until you have solid evidence of parasites.