This study provides an understanding of the feeding habit and intensity of the mudskipper Periophthalmodon septemradiatus, which was a potential aquarium pet, by analyzing its relative gut length (RGL) and gastro-somatic (GaSI) indexes. Fish specimens were caught with fishing rods in an area from the Hau River’s estuary in Soc Trang province to its upstream in An Giang province during a period of one year from August 2017 to July 2018. | VNU Journal of Science: Natural Sciences and Technology, Vol. 34, No. 3 (2018) 75-83 The Relative Gut Length and Gastro-Somatic Indices of the Mudskipper Periophthalmodon septemradiatus (Hamilton, 1822) from the Hau River Dinh Minh Quang1,*, Tran Thanh Lam2,3, Nguyen Thi Kieu Tien4 1 School of Education, Can Tho University, Can Tho, Vietnam Dat Lat University, 1 Phu Dong Thien Vuong, Ward 8, Da Lat, Lam Dong, Vietnam 3 Bac Lieu University, 178 Vo Thi Sau, Ward 8, Bac Lieu, Vietnam 4 An Khanh High School, Can Tho, Vietnam 2 Received 17 August 2018 Revised 04 September 2018; Accepted 06 September 2018 Abstract: This study provides an understanding of the feeding habit and intensity of the mudskipper Periophthalmodon septemradiatus, which was a potential aquarium pet, by analyzing its relative gut length (RGL) and gastro-somatic (GaSI) indexes. Fish specimens were caught with fishing rods in an area from the Hau River’s estuary in Soc Trang province to its upstream in An Giang province during a period of one year from August 2017 to July 2018. The analysis of 1,504 fish samples shows that RGL did not change by fish size, resulting in no change in the feeding habit of P. septemradiatus in relation to its size. By contrast, the feeding habit of this mudskipper varied by site, month and season of sample collection; accordingly, the RGL was also significantly different by site, month and season of sample collection; both the male and female fish fell into the carnivorous as the RGL was ) [5]. The GaSI was estimated as 100*Wg/W (Wg:weight of gut and W:fish body weight) and was used to estimate feeding intensity [6]. 77 . Data analysis The variations of RGL and GaSI with fish size, place and month were quantified by oneway ANOVA. The changes RGL and GaSI between the dry and the wet season were examined by T-test. The interaction of fish size, season and place on changes of RGL and GaSI was tested by General Linear Model. The significant difference of RGL of male
