He really needs to get a siphon as who knows what is lurking in the substrate. It is possibly dropsy but possibly their diet as the scales only seem to be sticking out in the tummy area, which they will if the fish are getting constipated or bloated. Tell him to try feeding them some cooked shelled pea and see if that helps. Also, what is he feeding them? Some of the cheaper brands of goldfish pellets and sticks etc I found tend to expand more than others when water is added so after the fish swallows it, it swells up in their digestive system and they have trouble getting it to go right through.