Dojo Loach (Misgurnus anguillicaudatus) Breeding Guide

Breeding the dojo / weather loach: sexing by the male pectoral lamina circularis, the encircling spawning embrace in vegetation, and why home spawns are rare and hormone induction is common.

Overview

Misgurnus anguillicaudatus is native to eastern Asia, from Siberia and Sakhalin through Korea, Japan and China to northern Vietnam. It is a cold-tolerant species; aquarium-kept fish typically reach around 15-20 cm, while wild specimens can grow larger. Captive breeding reports are rare and lack detail, and the species is likely induced to spawn using hormones for commercial and research purposes.

Sexing

Adult females are typically heavier-bodied and a little larger than males. In mature males the pectoral fins are enlarged with a thickened second ray forming a structure known as the lamina circularis, which in this species is rounded with a smooth posterior edge. Males also show horizontal body swellings behind the dorsal fin that are visible from above.

Conditioning

As an omnivore, the dojo loach should be conditioned on a varied diet. The closely related M. fossilis first spawns at two to three years of age at around 110 mm and breeds between March and July, which gives a rough indication of the maturity and seasonal window involved.

Spawning Behavior & Trigger

The female leads the male into dense vegetation such as filamentous algae, and as the eggs are released the male wraps his body around that of his mate, forming a complete ring. Seasonal change is the natural cue, mirroring the spring-to-summer spawning window seen in the related M. fossilis.

Common Challenges

Reliable, detailed home-spawning accounts are scarce, which makes the species difficult to breed without hormone induction. One unusual reproductive note is that a population on Hokkaido Island, Japan reproduces asexually through gynogenesis, an all-female lineage requiring sperm from a related species to trigger egg development.