Powder Black Tang (Acanthurus nigricans): Breeding Guide
Acanthurus nigricans shows facultative monogamous, territorial behavior and broadcasts its eggs into open water. Its pelagic acronurus larvae rule out home breeding of this Pacific surgeonfish.
Overview
The Powder Black Tang, Acanthurus nigricans, occurs in the eastern Indian Ocean at the Cocos-Keeling and Christmas Islands and across the Pacific from the Ryukyus and Great Barrier Reef to Hawaii and French Polynesia, with eastern Pacific records at the Revillagigedos, Cocos, Galapagos and the Mexican coast. FishBase gives a maximum fork length of 36 cm and a depth range of 0 to 67 m.
It is an algae grazer found solitarily or in groups, with shy juveniles sheltering among large corals. There are no records of this species being bred in captivity.
Spawning Behavior & Trigger
FishBase notes that monogamous mating is observed in A. nigricans as both facultative and social, and that adults are territorial. As in the genus generally, fertilization is external: gametes are broadcast into the open water column above the reef, typically at dusk and often around lunar phases when currents help disperse the eggs.
Even where a male and female associate, spawning is a brief open-water release rather than a guarded nest. Detailed species-level spawning timing for A. nigricans is not given in the consulted sources.
Egg & Fry Care
Eggs are pelagic and float away on the current. They hatch into transparent acronurus larvae that occupy the plankton for an extended period, which in surgeonfishes can last more than 39 days before the larvae settle.
Because the larvae must drift and feed in the open ocean, they cannot be reared in a home aquarium. Larval culture of surgeonfishes is limited to dedicated research aquaculture.
Common Challenges
- Even a facultatively monogamous pair spawns in open water, leaving no eggs to collect.
- Territorial aggression toward similar fish complicates keeping a compatible pair.
- The long pelagic acronurus stage cannot be supported on aquarium plankton.