New to the forum. I bought some peppermint Bristlenose about 8 months ago 5 in total for my tank. Four of the Peppermints are jet black but one is permanently discoloured. They were all black when i bought them but one has progressively lost his colour! I have read that they become "washed out" when stressed but I don't believe this to be the issue as they all seem to get along great and with no fights. He feeds really well on a varied diet and looks healthy. Just after some advice as to why he is like this? Is he some type of hybrid or inbred? He has white lips white around his fins. He is almost grey!