Synchiropus circularis Breeding Guide

The circled dragonet Synchiropus circularis is a small western-Pacific dragonet that, in common with its family, spawns by a dusk pair-ascent releasing pelagic eggs. Captive rearing is essentially unreported.

Overview

Synchiropus circularis, the circled dragonet, is a small reef-associated dragonet of the family Callionymidae reaching about 2.3 cm standard length. It occurs in the western Pacific from Malaysia, Indonesia and the Philippines to Papua New Guinea, Guam, the Northern Marianas and the Chesterfield Islands, over sand-rubble bottoms at depths of 2 to 35 m in warm water around 28 to 29 °C. Like other dragonets it forages for small benthic invertebrates.

Sexing

Dragonets are sexually dimorphic, with males larger and bearing longer, more elaborate fins; display males flare these fins prominently. This is the practical basis for distinguishing the sexes, since no species-specific colour key is published for Synchiropus circularis.

Conditioning

As a benthic-invertebrate feeder this species relies on live copepods to reach breeding condition. A mature reef or refugium with self-sustaining pod populations is the practical means of conditioning a pair.

Spawning Behavior & Trigger

Dragonet spawning occurs in the late afternoon just before sunset. Following a courtship display in which both fish fan their pectoral and caudal fins and the male flares his dorsal fins, the pair ascends roughly 0.7 to 1.2 m up the water column, moving semicircularly with the pectoral fins, and releases eggs and milt near the top of the ascent.

Egg & Fry Care

The eggs are buoyant and pelagic, intermingling with plankton, and the parents give no care after spawning. In aquaria the eggs must be captured as they rise and the resulting planktonic larvae require extremely small first foods, so rearing has only been accomplished in specialist setups.

Common Challenges

Collecting floating eggs before filtration removes them and feeding the minute larvae are the central obstacles, together with sustaining the copepod density needed for broodstock and fry. Reproduction is therefore seldom documented beyond egg release for this species.