Discoloration refers to the dark, pale or extremely bright colouring of the skin and not to red or white patches. (see p. 27+31)
Disruption of the colour pattern is especially conspicuous in Cichlids. (Ill. 150, 152, 156)
Malawi Cichlids may display black stripes caused by parasites (Black Stripe Syndrome).
Dark colouring is usually caused by a bacterial and/or parasitic infection (e.g., FishMB)
and bright, extreme colouring generally occurs in the last few hours of the fish?s death struggl
Goldfish and pond fish may exhibit black patches around a wound or ulcer (Ill. 155), caused by the extra formation of black pigment. These patches will disappear when cured.