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Understanding the gastrointestinal physiology and responses to feeding in air-breathing Anabantiform fishes

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  • Harriet R. Goodrich, The University of Queensland, University of Exeter
  • ,
  • Mark Bayley
  • Lina Birgersson, University of Gothenburg
  • ,
  • William G. Davison, University of Exeter
  • ,
  • Ora E. Johannsson, The University of British Columbia
  • ,
  • Anne B. Kim, The University of British Columbia
  • ,
  • Phuong Le My, Bac Lieu University
  • ,
  • Tran H. Tinh, Wageningen University and Research Centre
  • ,
  • Phuong N. Thanh, Can Tho University, Vietnam
  • ,
  • Huong Do Thi Thanh, Can Tho University, Vietnam
  • ,
  • Chris M. Wood, The University of British Columbia

The Mekong Delta is host to a large number of freshwater species, including a unique group of facultative air-breathing Anabantiforms. Of these, the striped snakehead (Channa striata), the climbing perch (Anabas testudineus), the giant gourami (Osphronemus goramy) and the snakeskin gourami (Trichogaster pectoralis) are major contributors to aquaculture production in Vietnam. The gastrointestinal responses to feeding in these four species are detailed here. Relative intestinal length was lowest in the snakehead, indicating carnivory, and 5.5-fold greater in the snakeskin, indicating herbivory; climbing perch and giant gourami were intermediate, indicating omnivory. N-waste excretion (ammonia-N + urea-N) was greatest in the carnivorous snakehead and least in the herbivorous snakeskin, whereas the opposite trend was observed for net K+ excretion. Similarly, the more carnivorous species had a greater stomach acidity than the more herbivorous species. Measurements of acid–base flux to water indicated that the greatest postprandial alkaline tide occurred in the snakehead and a potential acidic tide in the snakeskin. Additional findings of interest were high levels of both PCO2 (up to 40 mmHg) and HCO3 (up to 33 mM) in the intestinal chyme of all four of these air-breathing species. Using in vitro gut sac preparations of the climbing perch, it was shown that the intestinal net absorption of fluid, Na+ and HCO3 was upregulated by feeding but not net Cl uptake, glucose uptake or K+ secretion. Upregulated net absorption of HCO3 suggests that the high chyme (HCO3 ) does not result from secretion by the intestinal epithelium. The possibility of ventilatory control of PCO2 to regulate postprandial acid–base balance in these air-breathing fish is discussed.

OriginalsprogEngelsk
TidsskriftJournal of Fish Biology
Vol/bind96
Nummer4
Sider (fra-til)986-1003
Antal sider18
ISSN0022-1112
DOI
StatusUdgivet - 2020

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