Ornamental Fish Production and Management (1+1)

11.2.1 Goldfish

The goldfish is a domesticated form of the so called Crucian carp, Carassius carassius, which is still widely distributed in Asia as well as in Eastern Europe. The wild fish are generally of a silver appearance. The colouration and other aspects of present-day goldfish are believed to have been developed from the wild type, somewhere in China, before the 16^th Century. They are reported to have been introduced into Japan in the same century and into Europe about 100 years later. Various explanations for their quite distinctive colouration have been given of which the most rational are selective breeding from albino stock, distant hybridization and degradation of pigment cells by virus particles. Whatever the genetic basis, the gold colour appears during the early months of life of the fish and seems to involve the progressive depigmentation or destruction of melanophores. The brilliance of the final colour is probably determined environmentally. The goldfish of warmer climates, Israel or India, for example, certainly seem to be a vastly more colouful appearance than those reared in the cooler temperate regions of Europe.

There are three basic body colours in goldfish varieties. The commonest is the rich red-gold appearance, but all-black is typical of some forms and the well known shubunkin exhibits a blue, red and black mottled appearance plus the transparent scale characteristics. Kirpichnikov (1981) reviewed evidence on the genetic control of these major colour variants. Blue is reported to be determined by a simple Mendelian recessive with brown colouration under more complex control. Depigmentation itself is described as under control of two distant loci, the recessive allele of which confer the black colouration.

The fin and body shape of goldfish are also of great antiquity but have undergone much recent development. The range of varieties is very large – including body colour, these are reputed to be almost 100 individual strains of goldfish i.e. forms for which body proportions and colours have been defined for the purpose of selective breeding for show purposes. Selective breeding is likely to be feasible for modification of such fin and body shape traits. Selection by culling can be very efficient where visible criteria are employed and where fecundity is large as in most fish species.