Showa Koi Breeding Guide

How to breed Showa koi (Cyprinus carpio), a pond egg-scattering variety that spawns in spring; the black-based red-and-white pattern comes from selective culling.

Overview

Showa (Showa Sanke) is a variety of koi (Cyprinus carpio): a black koi with red and white markings, another classic three-colour variety. Koi are large pond fish, so breeding is an outdoor pond project rather than an aquarium one. All koi varieties result from selective breeding, and the Showa pattern is fixed only by systematically culling undesirable offspring during development.

Conditioning

Koi benefit from being kept in the 15–25 °C (59–77 °F) range, and their immune systems are very weak below 10 °C (50 °F), so conditioning mature breeders in stable, warm-season water supports a healthy spawn.

Breeding Setup

Spawning is set up in a pond with a target for the sticky eggs to attach to. A sticky outer shell around each egg helps keep it in place so it does not float around, so spawning ropes, brushes or fine plants are provided as a receiving surface.

Spawning Behavior & Trigger

When koi naturally breed on their own they tend to spawn in the spring and summer seasons. The male starts following the female, swimming right behind her and nudging her. After the female releases her eggs they sink to the bottom of the pond and stay there, held in place by the sticky shell.

Egg & Fry Care

Koi produce thousands of eggs per spawning, though many of the fry do not survive due to being eaten by others. Because of the high losses, separating eggs or fry from the adults improves survival.

Common Challenges

Even from the best champion-grade koi, most offspring are not acceptable as nishikigoi — they may have no interesting colors or even be genetically defective — so expert culling is required. For Showa the goal is a black base carrying balanced red and white markings.