2. Materials and methods
2.1. Fish types
Pictures of fish, representatives of the phenotypes that were studied are presented in Fig. 1. The pictures in Fig. la are cross-tabulated so that in rows are the three red phenotypes (transparent, red patches and completely red) and in columns are the three black phenotypes (absence of black color, Bekko pattern and บtsuri pattern). Red is defined as a completely red fish, while Kohaku always lacks red to some extent. The Bekko koi has black dots (relatively low black coverage) while the บtsuri pattern comprise large black patches. Fig. lb demonstrates Kohaku variants with three coverage rates: “1/3” for Kohaku with red patches covering the front third of the body, “2/3” for those with red patches over the front two thirds of the body, and “3/3” for Kohaku with red patches over the whole body. We have also used Kohaku parents with either “high” (over 50%) or “low” (under 50%) red coverage for this purpose. Names of the koi variants are common terms as used by the Japanese koi breeders (see McDowall, 1989 for the classical definitions of names and variants). Parents used for this study were all from commercial Israeli farms, mostly from the Gan-Shmuel fish breeding center. Parents used are descendents of koi imported from either Japan or Europe during the last 20 years. No pedigree information is available. Renewal of broodstocks in the farm involves selecting high quality offspring from crosses, usually between similar phenotypes.