The Relative Gut Length and Gastro-somaticindexes of the Mudskipper Periophthalmodon septemradiatus (Hamilton, 1822) from the HauRiver

Abstract

This study provided an understanding of feeding habit and intensity of the mudskipper Periophthalmodon septemradiatus, which was a potential aquarium pet, by analyzing the relative gut length (RGL) andgastro-somatic (GaSI) indexes. Fish specimens were caught by fishing rods from the estuary in Soc Trang province to the upstream in An Giang province of Hau River during a period of one year from August 2017 to July 2018. Data analysis of a collection of 1,504 fishes showed that RGL did not change with fish size, resulting in the feeding habit of P. septemradiatus did not change with fish size. By contrast, the feeding habit of this mudskipper varied with place, month and season as the RGL significantly different between place, month and season, but both males and females fall into carnivorous fish as RGL was <1. Similarly, the feeding intensity of this specice did not change with fish size, as the GaSI was not significantly different among four fish size groups. Meanwhile, the mudskipper displayed spatial, temporal and seasonal variations in feeding intensity since GaSI significantly changed with place, month and season. The changes of feeding habit and intensity of P. Septemradiatus were not regulated by the interaction of fish size and place, fish size and season, and place and season. These results provided new knowledge on feeding habit and intensity of this fish specice, being used for the understanding of fish adaption and conservation in the study region.
 Keywords
 Gastro-somatic index, mudskipper, Periophthalmodon septemradiatus, relative gut length
 References
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Foraging ecology of the amphibious mudskipper Periophthalmus chrysospilos (Gobiiformes: Gobiidae)

“…The highest RGL values were disproportionately recorded from specimens collected at DDCM, an area with the highest flora diversity amongst sites. The variation in RGL values between sites was also reported in other confamilial taxa— Periophthalmodon septemradiatus ( Dinh, Tran & Nguyen, 2018 ) and Butis koilomatodon ( Nguyen, Lam & Dinh, 2020 )—from the Mekong Delta. The varied diet composition of this amphibious fish species reflects the habitat in which it resides and the interactions between marine and terrestrial biota within the intertidal areas.…”

“…Some species, such as those from the genus Boleophthalmus , are less tolerant to desiccation, stay close to the waterline, and graze the substrate surface for diatoms ( Ravi, 2013 ; Dinh, 2015 ). Others, such as species of Periophthalmodon , are carnivorous and are known to traverse upriver to areas unaffected by tidal cycles ( Dinh, 2018a , 2018b ; Dinh, Tran & Nguyen, 2018 ; Dinh et al, 2020b ).…”

Morfometrik Sistem Pencernaan Ikan Nila (Oreochromis niloticus) yang Dipapar Limbah Cair Kelapa Sawit

“…Walaupun terjadi peningkatan nilai GaSI pada ikan yang dipapar polutan, perilaku makannya malah menunjukkan peningkatan intensitas makan yang tinggi (Quang, et al, 2018). Menurut Kurbah dan Bhuyan (2018), penurunan nilai GaSI disebabkan oleh beberapa faktor, seperti tidak tersedianya bahan makanan.…”