super red plecs

i have several super reds which are now starting to come of size were then can be sexed but recently there is one which has gone to almost a cream colour is this just down to stress or has anybody else had this happen and if so how was it rectified, it has been the same as the rest until about 3 weeks ago when it has seemed to have faded
atb
kev

If the are like mine they will lighten in color & get really thin, then die. Lots of times this happens between 1 & 1.5 inches, but I have one male that is 2+ inches that is getting light colored. I have been breeding them for 3 years & I think this is due to them being inbreed for the red color. This is why I have been raising all my super reds to adulthood to sell. When I first started selling fry, I had sold a few people 20  super reds & they had a least 1/2 die from the same condition as yours are having. I've tried all types of medications & nothing has helped so far. Let me know if you find a cure