Tiny white pimple-like bumps on the head and gills of male goldfish are perfectly normal in the breeding season. However, large white patches and cotton woll like growths are a dangerous sign of ill-health. Cotton wool disease is a common fungal infection which can kill fish eggs and will infect fish where their scales are damaged. Larger fish can be treated with an anti-fungal preparation but small fish or infected eggs should be destroyed. Fugal diseases do not happen if pool hygiene is good. Blueish-white slimy areas on a fish indicate skin disease which can irritate the fish so much that it swims against hard surfaces and vegetation to relieve the distress. These are caused by small organisms and can be treated using cures designed to rid the fish of parasites. White spot disease usually affects new fish. Caused by a parasite which burrows into the skin it must be treated early when the characteristic small spots on the tail or fin are first seen. Good pet shops and garden centres usually sell a number of proprietary remedies.