Biometrics and Sexual dimorphism of Neolissochilus hexagonolepis (McClelland)

 

Author(s): Boni Amin Laskar, Debajit Sarma, Debangshu Narayan Das

Abstract: Understanding the sexual dimorphism in fish is an uphill task and is paradoxical in different species. In general, the studies on the biometrics of fish form the basis of fishery investigations particularly in the management and exploitation of fishery resources. The present study was carried in order to obtain characteristic relationship of various morphological parameters between the sexes of Neolissochilus hexagonolepis (McClelland). Considerable differences in the percentage of some morphometric characters on standard length have been observed between males and females. The males were found to have greater head width at operculum, snout length, predorsal length and preanal length than the females. On the other hand, the females had greater body depth at dorsal fin insertion, pectoral fin length, anal fin height and ventral fin height than the males. The males were found to have greater value of biometric index for body depth at dorsal fin insertion, pectoral fin length, anal fin height and height of ventral fin than the females; while the females had greater values for head width at operculum, snout length, predorsal length and preanal length. The variation in the biometric index and percentage of anal fin height on standard length was highly significant between males and females. Together the values of correlation coefficient ‘r’ between the variable characters and the standard length were found positive, with the highest value of regression coefficient ‘b’ in case of total length (b=1.3082) and lowest in case of head height at eye (b=0.0366).

Differences in percentage on standard length of external sexual characters between sexes. A total of eight parameters are shown. In order to clearly visualize the distinction, the difference values for each of the parameters are taken and the particular parameter being greater in each of the sexes are shown. *symbolic expression of the parameters are such as: A= Anal fin height, B= Body depth at dorsal fin insertion, C= Pectoral fin length, D= Height of ventral fin, E= Head wide at operculum, F= Snout length, G= Predorsal length, H= Preanal length.

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