im just about to get 5 discus from someone i know thats shutting their tank down and they have the same peppering on the face that until reading through this i hadn't seen before
my tank also has black sand and a black 3d background but the tank they are coming from has white sand and a darkish background but not black
did you ever find out if the peppering was caused by the dark environment? i don't think it would bother me anyway cos they are so colourful but they do have the peppering in a tank with white sand? maybe its not just the environment that does it i have read something about genes?
i may have missed it reading through this thread seeing as its full of so much information looks good though!