The Nacteous (Mottled) Group of the Goldfish (Carassius auratus L.), with an Analysis of the Colours Seen in these Fish

Abstract

The colours of nacreous (mottled) fish are usually mottled but specimens do occur in which only one kind of the black, orange, or yellow chromatophores is present, while some lack pigments over most of the body. The colours appear metallic, pearl, or matt depending on the presence or absence of reflecting tissue in two definite layers. The hues seen in these fish are black, smoke, blue, orange, yellow, blood-red, and silver, which occur singly or in combinations. These hues are produced by black, orange, and yellow pigments in chromatophores, silver reflectillg tissue, and haemoglobin in the blood. The presence of a yellow pigment — a carotenoid — is reported for the first time. Although the colour red has been reported no red pigment has ever been described. An intense orange pigment will produce a red effect on a pale blood-red background.

The nacreous (mottled) group of the goldfish is intermediate between the metallic (scaled) and matt (transparent) groups with regard to the amount of reflecting tissue. The colours of these fish may not be used as criteria of the groups.