Inheritance and Expression of Koi Color Dominant Mutations in Koi × Goldfish Hybrids.

This article investigates the inheritance and expression of two dominant koi color mutations, "design" (D) and "red eyes" (R), in hybrids between koi (Cyprinus carpio) and Goldfish (Carassius auratus). The "design" mutation, characterized by a yellow dorsal stripe and head ornament, and the "red eyes" mutation, a dominant demelanization trait distinct from albinism, were both expressed in the hybrids, following Mendelian inheritance patterns consistent with heterozygous koi females crossed with wild-type Goldfish males. The "design" mutation produced "ghost fish" with a distinct color pattern, while the "red eyes" mutation resulted in juveniles with yellow and brown body colors but black eyes. These colored koi × Goldfish hybrids may have practical applications in aquatic weed control due to their identifiable phenotypes and reduced fertility compared to pure Common Carp.