Butterfly fishes are widely distributed throughout the Indo-Pacific Ocean and are often caught in large quantity by shrimp trawlers as a by-catch species. These fish are ecologically and commercially important, as they are ecological indicators of coral health and a major component of ornamental and by-product fisheries. However, owing to their low value for direct human consumption as a food, there is dearth of research on their demographics and life–history traits. The present study was therefore conducted using Heniochus acuminatus, one of the common butterfly fish that is captured as a by-catch in the Gulf of Mannar (GoM) to generate basic data on its demographic estimates. Specimens (n = 833) were collected monthly from the four reef-fish landing stations for two consecutive years and the demographic parameters were estimated using a FAO–ICLARM Stock Assessment Tool (FiSAT). Fish in the length class of 10–11 cm dominated the landings. The length-weight relationship (LWR) was defined as the equation, BW = 0.0234TL^3.156 suggesting positive allometric growth pattern of H. acuminatus in GoM. Estimated demographic parameters (asymptotic length, L_∞ = 17.85 cm) showed low growth rate and growth performance index (K = 0.95 and ϕ = 2.481 respectively) in study species. The estimated potential longevity (t_max) and the observed length at first capture (Lc) were found to be 3.15 years and 7.9 cm respectively. The higher natural mortality rate (M = 2.00 yr⁻¹) than the fishing mortality rate (F = 0.39 yr⁻¹) with exploitation level (E = 0.16) below the optimum level indicates that the state of the stock of H. acuminatus in the GoM is sustainable. The current study provides the first population demographic report of the genus Heniochus and is likely to have a significant conservation and commercial impact.

蝴蝶鱼广泛分布于整个印度洋-太平洋，通常被虾拖网渔船作为副渔获物大量捕捞。这些鱼在生态和商业上都很重要，因为它们是珊瑚健康的生态指标，也是观赏和副产品渔业的主要组成部分。但是，由于它们作为人类直接食用的食品价值较低，因此缺乏有关其人口统计和生活史特征的研究。因此，本研究是使用Heniochus acuminatus（一种常见的蝴蝶鱼）进行的，该鱼是在马纳那湾（GoM）捕获的副渔获物，以生成有关其人口统计估计的基本数据。标本（ñ 连续两年每月从四个珊瑚礁登陆站每月收集833头），并使用FAO–ICLARM种群评估工具（FiSAT）估算人口参数。长度在10-11厘米的鱼类占主导地位。长度权重关系（LWR）定义为等式，BW = 0.0234TL ^3.156提示的正异速生长图案H.渐尖墨西哥湾。估计人口统计参数（渐近长度，大号_∞  =17.85厘米）显示出低生长速率和生长性能指数（ķ  = 0.95和φ 在研究物种= 2.481分别）。估计的潜在寿命（t _max），首次捕获的观察长度（Lc）分别为3.15年和7.9 cm。较高的天然死亡率（中号 = 2.00年^-1）大于渔死亡率（˚F  = 0.39年^-1）与开采水平（Ë 低于最佳水平= 0.16）表示的库存状态H.渐尖在GoM是可持续的。本研究提供了Heniochus属的第一份人口统计学报告，并且可能对保护和商业产生重大影响。