peppering

Hello, I have a tank with some discus fish. Initially I had black gravel and no backing and my blue diamond turned very dark almost black himself. I have removed the black and and ordered a light blue background. I was wondering if I use the dark blue gravel I already have should he lighten up...

Hi, About three months ago one of my discus accumulated so many little black spots that he effectively half turned black. Apart from the visual deformation there were no changes to his appetite or behaviour around the tank, consequently I put the change down to a very severe and sudden case of...