Threadfins (Perciformes: Polynemidae) are commercially important, highly prized table fishes in India. In this study, we analysed the mitochondrial COI gene for validating species identification and phylogeny of threadfins occurring in Indian waters. Consequently, we developed barcodes for ten polynemids belonging to the genera Polydactylus, Eleutheronema, Leptomelanosoma, Filimanus and Polynemus. The K2P distance within the polynemid species in Indian waters ranged from zero to 0.8%. Nucleotide composition was estimated as adenine (A) = 22.5%, thymine (T) = 28.7%, cytosine (C) = 29.7% and guanine (G) = 19.1%. The average transitional pairs (75.8) were more frequent than the average transversional pairs (24.2) with an estimated Transition/Transversion bias (R) of 3.33. Cryptic species were observed in Polydactylus and Eleutheronema indicating the need for detailed studies on the taxonomy of polynemids globally. The present study determines the utility of DNA barcodes in species identification in polynemids.

线鳍鱼（Perciformes：Polynemidae）在印度是具有重要商业价值和价值的食用鱼。在这项研究中，我们分析了线粒体 COI 基因，以验证印度水域中线鳍的物种鉴定和系统发育。因此，我们开发了属于属10 polynemids条形码 Polydactylus，Eleutheronema，Leptomelanosoma，Filimanus和Polynemus. 印度水域中 polynemid 物种内的 K2P 距离从 0 到 0.8% 不等。核苷酸组成估计为腺嘌呤 (A) = 22.5%、胸腺嘧啶 (T) = 28.7%、胞嘧啶 (C) = 29.7% 和鸟嘌呤 (G) = 19.1%。平均转换对 (75.8) 比平均转换对 (24.2) 更频繁，估计转换/转换偏差 (R) 为 3.33。在Polydactylus和Eleutheronema中观察到隐性物种， 表明需要对全球多线虫的分类进行详细研究。本研究确定了 DNA 条形码在多线虫物种鉴定中的效用。