Weird sickness?

So cheech went a weird color his front half ended up paper and the back end was darker. His rays started falling to bits. This all happened over night. The PH was greatly high (my tap ph is 7.9 I've got it down now to normal) and there are 4 other fish in that divided tank and there's nothing wrong with them at all


I can't attach a pic ATM ill try hookig iPod onto of later to get it but have since put him down ;(