Chronixis Mimic Tang (Acanthurus chronixis): Breeding Guide

Acanthurus chronixis is a rare, possibly atoll-endemic surgeonfish that reproduces by open-water broadcast spawning like its genus. Its pelagic larvae make captive breeding unrealistic.

Overview

The Chronixis Surgeonfish, Acanthurus chronixis, is recorded by FishBase from Kapingamarangi Atoll in the Caroline Islands of the Western Pacific and is possibly endemic to that atoll. It reaches a maximum total length of 28 cm and lives in shallow water from 0 to 6 m over sand and coral bottoms of clear channels. FishBase lists it as rare and not commercial, with an IUCN status of Vulnerable.

Because of its rarity it is uncommon in the aquarium trade, and no captive breeding has been documented for this species.

Spawning Behavior & Trigger

No species-specific spawning data is available for A. chronixis in the consulted sources. As a member of Acanthurus, it is expected to be a pelagic broadcast spawner: surgeonfishes of this genus generally spawn at dusk in short pair- or group-spawning ascents near the reef edge, often around lunar phases when currents carry off the gametes.

Fertilization in such spawning is external, with no nest or parental care. Given its very limited shallow-channel habitat, spawning likely takes place near those clear-water channels, though this has not been described in the sources used.

Egg & Fry Care

Following the genus pattern, the eggs would be pelagic and float in the open water, hatching into transparent acronurus larvae. In surgeonfishes this planktonic larval stage can last more than 39 days before settlement.

Such a long oceanic drift on natural plankton cannot be reproduced in a tank, so home rearing is not feasible. Larval culture of surgeonfishes remains a research-aquaculture endeavor.

Common Challenges

• The species is rare and seldom available, so even obtaining a potential pair is difficult.
• Open-water spawning leaves no eggs or nest to manage in captivity.
• The pelagic acronurus larvae depend on ocean plankton that aquariums cannot supply.