Sexual dimorphism in structures, size and shape of the cyprinid Nilgiri melon barb, Haludaria fasciata

The morphological differences between the sexes of a species is relevant to its captive breeding, ethology, and eco-biology and are studied extensively in fishes. In this paper, we analyzed the sexual dimorphism of the cyprinid Nilgiri melon barb, Haludaria fasciata (Jerdon), in their external structures, size, and shape. Physical examination, microscopical analysis, and morphometric and geometrical analyses of both sexes of the fish were conducted. The presence of tubercle pits and protuberant tubercles on the snout and orbital region were observed in males, while these were absent in females. Smaller-sized tubercles were arranged like a serration on the pectoral fin of males. Body size analysis indicated significant sexual size differences (P < 0.05) in body depth, fork length, eye diameter, pectoral fin length, and caudal fin length. Shape analysis indicated that the coordinate lengths L8 and L1 were the two that were significantly different (P < 0.05) between the sexes. In global redundancy trace analysis of vertices, the males in the population had more substantial variations in their shapes than did females. The paper discusses the possible functions linked with the dimorphic traits identified in H. fasciata.