The variations of Clark and Gastrosomatic indexes of Glossogobius giuris living in some regions the Mekong Delta, Vietnam

This study lasted one year to describe the energy accumulating capacity and feeding intensity of Glossogobius giuris by analyzing the Clark index and Gastro-somatic (GaSI) indexes of this species. A total of 1,291 individuals were collected in four sites, including Cai Rang, Can Tho; Long Phu, Soc Trang; Hoa Binh, Bac Lieu and Dam Doi, Ca Mau. In each sampling site, fish were monthly caught using trawl nets from January to December 2020. The data analysis results showed that the fish species displayed high energy accumulating capacity due high value of the Clark index. This capacity varied between males and females, immature and mature groups, and four sites, but not between the dry and wet seasons as Clark changed with gender, fish size and location but not the season. With a high value of GaSI, the goby showed high feeding intensity. This fish showed intraspecific and spatiotemporal changes in feeding intensity since GaSI varied with fish size, season and location. The gender ´ season interaction affected GaSI but not Clark, whereas the reverse case was found in gender ´ site interaction. These indexes were influenced by the season-site interaction. The findings are helpful for fish’s adaption understanding and future artificial cultivation study.