Determination of sexual dimorphism of African snakehead (Parachanna obscura): morphometric and meristic parameters, weight-length relationship and condition factor

Abstract

Artificial reproduction of fishes requires knowledge of their sexual dimorphism. African snakehead, Parachanna obscura, sexual dimorphism determination is difficult trough urogenital orifice examination. The aim of this study was to determine the sexual dimorphism of P. obscura using the parameters such as morphometric parameters, meristic parameters, weight-length relationship and condition factor. For the study, 30 specimens of P. obscura were collected from a swamp in Sakete a southeastern district of Benin. The fish weighed between 117 g and 251 g and their length were between 24.40 cm and 32.20 cm. At the end of this study, the different fins ray number were not significantly different (P>0.05). There was no significant difference among male and female fish (P>0.05) in total length, standard length, head length, snout length, snout width, head circumference and body circumference. Tail length had a significantly difference between male and female (P<0.05). The weight-length relationship indicated an allometric growth for the males and an isometric growth for the females. Significant difference was observed between male and female in condition factor (P<0.05). The male condition factor was the double of female condition factor. Condition factor, tail length and weight-length can be used for P. obscura sexual dimorphism determination.

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Keywords:  Parachanna obscura, sexual dimorphism, condition factor, weight-length relationship