Studies on the inheritance of black patches in ornamental (koi) carp

The ratio of fish with and without black pigmentation was determined in 22 amphimictic, two meiotic gynogenetic and two mitotic gynogenetic progenies produced from koi parents of different color types. The results of analysis of the amphimictic progenies confirmed the proposed earlier hypothesis tha t the development of black patches in koi is controlled by one dominant gen e (Bl). Koi parents with black patches (white-red-black and white-black) pr oved to be heterozygotes for a gene determining black pigmentation (genotyp e Blbl). Crosses between them resulted in a segregation of 3:1 (pigmented:u npigmented), while their crossing with white-red koi (without black patches ; genotype blbl) resulted in a segregation of 1:I. One F-1 male with the ge notype BlBl was identified by performing test crosses. The segregation of f ry in gynogenetic progenies depended on the type of gynogenesis, and genera lly fitted the expected ratios. The results of gynogenetic experiments also confirmed the occurrence of the BI gene.