The farming of several species in aquaculture often produces pale coloured fish due to a deficiency in dietary carotenoid sources compared to their wild caught counterparts, resulting in the loss of market value and consumer acceptance. Supplementation of feed with astaxanthin as a carotenoid source has since been found to enhance red colouration in several important fish species. In this study, comparative transcriptome analysis was performed on the skin from the main body (dorsolateral region) and caudal fin of Malabar snappers (Lutjanus malabaricus) fed with and without astaxanthin over a 32-day period to identify genes related to the trait. All clean reads were assembled into 205,940 unigenes with a N50 of 2079 bp. A total of 881 and 178 differentially expressed genes (DEGs) between Control Body (CB) vs Treatment Body (TB) and Control Fin (CF) vs Treatment Fin (TF) were identified respectively, where expression patterns suggested that pigment-related genes bco1, bco2l, pax7, slc7a11, hsp70, and stard5 are key genes involved in the enhancement of red colouration in Malabar snappers. Metabolic pathways related to pigmentation such as PI3k-Akt, MAPK, Wnt, cAMP, and Ras signaling are likely to play vital roles in the enhancement of red colouration in juvenile Malabar snappers. In addition, numerous immune-related genes were found to be differentially expressed for both CB vs TB and CF vs TF, suggesting the potential use of dietary astaxanthin as an immunostimulant. The present study provides a foundation to the understanding of the molecular mechanisms involved in carotenoid-induced colouration, and development of breeding and culture practices to produce farmed Malabar snappers with the desired consumer-favoured traits.

由于与野生捕获的同类相比，膳食类胡萝卜素来源缺乏，水产养殖中的几种鱼种的养殖通常会产生浅色鱼，从而导致市场价值和消费者接受度的损失。已经发现添加虾青素作为类胡萝卜素来源的饲料可以增强几种重要鱼类的红色。在这项研究中，对在 32 天内喂食和不喂虾青素的马拉巴鲷鱼（ Lutjanus malabaricus ）的主体（背外侧区域）和尾鳍的皮肤进行了比较转录组分析，以鉴定与该性状相关的基因。所有干净的读数都组装成 205,940 个 unigenes，N50 为 2079 bp。对照体 (CB) 之间共有 881 和 178 个差异表达基因 (DEG)分别鉴定了vs治疗体 (TB) 和对照鳍 ( CF ) vs治疗鳍 (TF)，其中表达模式表明色素相关基因bco1、bco2l、pax7、slc7a11、hsp70和stard5是参与增强的关键基因马拉巴尔鲷鱼的红色。与色素沉着相关的代谢途径，如 PI3k-Akt、MAPK、Wnt、cAMP 和 Ras 信号传导可能在增强幼年马拉巴尔笛鲷的红色中起重要作用。此外，许多免疫相关基因被发现在 CB与TB 和CF vs TF，表明食用虾青素作为免疫刺激剂的潜在用途。本研究为了解类胡萝卜素诱导的着色所涉及的分子机制以及开发育种和培养实践以生产具有所需消费者喜爱的性状的养殖马拉巴尔鲷鱼提供了基础。