No abstract

This study supplemented the way of sex determination of fish based on the regression relationship of some morphological indicators of Mystus mysticetus. A total of 425 fish specimens were collected by trawl nets at Cai Rang - Can Tho and Long Phu - Soc Trang from January to July 2022. After collection, the fish were transferred to the laboratory to determine their total length (TL), standard length (SL), eye diameter (ED), eye distance (DE), body height (BD), head length (HL), and mouth width (MD) before anatomy for sex determination based on gonads. The regression analysis results of TL-SL, TL-ED, TL-DE, TL-BD, TL-HL, and TL-MD showed that SL, DE, and MD could be used to determine the sex of this fish species because SL and DE were dominant in growth in males, and MD was prevalent in females. In addition, SL could be used to determine the sampling time and HL to determine the distribution environment.

Mystus mysticetus, a member of the Bagridae family, is represented by three dark longitudinal stripes running vertically below the lateral line, a dark black spot at the back of the operculum, a gray-black margin, an adipose dorsal fin that is short-tall and quite a distance from the dorsal fin (Phan et al., 2022;Tran et al., 2013;Vo et al., 2021). The Mystus is of genera of the family Bagridae, a family of fish native to Africa and Asia (Berg, 1858), with about 21 genera and 89 species (Fricke et al., 2022). In Vietnam, species of the genus Mystus are concentrated in the Mekong Delta (VMD) and some other localities in the central and northern regions of Vietnam.According to FAO, in the Mekong River basin, there are 13 species of the genus Mystus, typically M. atrifasciatus (Fowler, 1937), M. vittatus