Inheritance of Sparkling Scales (Ginrin) Trait in Ornamental Koi Carp

The purpose of this study was to investigate mechanisms of inheritance of the sparkling scales (ginrin) trait in ornamental koi, a variant of Common Carp Cyprinus carpio. The fish segregations of ginrin : nonginrin were recorded in three F1 progenies obtained by crosses of ginrin × nonginrin and 16 F2 progenies obtained by crosses of ginrin × ginrin and nonginrin × nonginrin. The segregations of ginrin : nonginrin in most F1 progenies did not differ significantly from the 1:1 Mendelian ratio, while crossing nonginrin fish from F1 progenies resulted in the appearance of only nonginrin fish in F2. Based on these data, it was suggested that the ginrin trait in koi is controlled by a dominant mutation of one gene (Gr/gr): fish with genotypes GrGr and Grgr have ginrin phenotype, while fish with genotype grgr do not possess this trait. In most analyzed F2 progenies obtained by crosses of ginrin × ginrin, the ginrin : nonginrin segregations were statistically different from the 3:1 and 2:1 theoretical ratios with permanent deficit of ginrin fish. It was suggested that the deviation of segregations from theoretical ratios resulted from increased mortality of ginrin fish as a result of possible negative pleiotropic effect of ginrin mutation on fish survival. The negative pleiotropic effect of ginrin mutation on fish growth was detected; nonginrin fish were substantially larger and heavier than ginrin fish from the same progenies raised in the same outdoor tanks.