Breeding the Bluestriped Fangblenny (Plagiotremus rhinorhynchos)

Plagiotremus rhinorhynchos is a cleaner-wrasse-mimicking blenny that feeds on the mucus and scales of other fish; it lays demersal adhesive eggs but its predatory habits complicate captive breeding.

Overview

Plagiotremus rhinorhynchos (family Blenniidae), the bluestriped fangblenny, ranges throughout the Indo-Pacific and reaches about 12 cm standard length at depths of 1-40 m. FishBase notes it feeds on the skin, mucus and sometimes scales of other fishes by quick attacks, and that juveniles mimic the cleaner wrasse Labroides dimidiatus. Adults shelter in deserted worm tubes and small holes.

Sexing

FishBase records the species as oviparous with distinct pairing. No reliable external sexing characters are documented for the aquarium, so a compatible male-female pair is recognised by pairing and the shared occupation and defence of a tube refuge.

Breeding Setup

A breeding attempt requires a species-appropriate system with narrow tubes or holes the fish can retreat into and defend, mirroring the deserted worm tubes it uses in the wild. Because it bites the mucus and scales of tankmates, it should be kept without vulnerable fish during breeding trials.

Spawning Behavior & Trigger

Reproduction follows the blenny pattern of distinct pairing, with the female depositing eggs inside a tube or hole that the male typically fertilises and guards. The tubular refuge the fish uses for shelter serves as the spawning site.

Egg & Fry Care

Eggs are demersal and adhesive, attached to the substrate by a filamentous adhesive pad or pedestal, and larvae hatch as planktonic forms found in shallow coastal waters. Rearing these larvae requires a dedicated larval system and graded live foods.

Common Challenges

Beyond the difficult planktonic larval phase, the species' habit of biting the mucus and scales of other fish makes it hard to house with the tankmates a community breeding system would otherwise allow, and emerging fry behavior is poorly documented.