Breeding Ginrin Koi

How to breed Cyprinus carpio var. Ginrin: a pond egg-scatterer spawning in spring, with the metallic Ginrin scale trait and demanding professional-level fry selection.

Overview

Ginrin Koi (Cyprinus carpio var. Ginrin) is a koi line distinguished by sparkling, metallic-reflective scales that overlay any colour pattern; Ginrin versions exist for almost all other koi varieties. As with koi generally, breeding is a pond-based, egg-scattering process. Koi naturally breed in spring and summer.

Conditioning

Koi spawn as the water warms into spring and summer, so breeding stock are typically held in the pond through the warming season. Koi do best when kept in the 15-25 degrees C (59-77 degrees F) range; their immune systems weaken below 10 degrees C, so robust, well-fed parents in good condition are the starting point.

Spawning Behavior & Trigger

Spawning is triggered by rising spring water temperatures. The male begins following the female closely, swimming right behind her and nudging her. The female then releases her eggs, which the male fertilises as they are scattered. Koi produce thousands of offspring from a single spawning.

Egg & Fry Care

After release, the eggs sink to the bottom of the pond and stay there; a sticky outer shell around each egg helps keep it in place. Many of the fry do not survive because they are eaten by other fish, so eggs and fry are best protected from adults. Nurturing the resulting fry is a tricky and tedious job usually done only by professionals.

Common Challenges

Even from the best champion-grade parents, the large majority of offspring are not acceptable for retention, so heavy selection (culling) is required. Predation on eggs and fry within the pond further reduces yield, making fry rearing the most demanding part of the process.