(Linnaeus, 1758)
1. Distinctive characteristics of early developmental stages
(a) Eggs
Not represented in the mangroves.
(b) Early juveniles (Based on 29.5 mm T.L. specimens)
Acanthurus nigricans 1
The body is laterally compressed. The dorsal fin has 9 spines and 26 rays. The anal fin has 3 spines and 23 soft rays. Lancet-like spines on each side of caudal peduncle are yet to form at this stage. Instead, dark pigmentation develops at the narrow caudal peduncle. The caudal fin is truncated at this stage. Pigmented patches extend from nape to breast through the eyes and pectoral fin base. Pigment is scattered all over the body, which is almost yellowish-white in colour at this stage (it usually becomes dark brown in juvenile and adult stages).
2. Salient biological characteristics
It grows to a maximum size of around 350 mm in length in coastal and coral seas. Studies regarding the biology of this species are limited.
3. Salient ecological information
It occurs in coral reef areas. The juveniles are sporadic visitors to the mangroves and are collected from the lower reaches.