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. Here we detail the gastrointestinal responses to feeding in these four species. Relative intestinal length was lowest in the snakehead, indicative of carnivory, and 5.5-fold greater in the snakeskin, indicative of herbivory; climbing perch and giant gourami were intermediate, suggesting omnivory. N-waste excretion (ammonia-N + urea-N) was greatest in the carnivorous snakehead and least in the herbivorous snakeskin, while the opposite trend was seen 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 the water suggested 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, we show that intestinal net absorption of fluid, Na+ , and HCO3 - are 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. This article is protected by copyright. All rights reserved.

中文翻译：

---

了解呼吸空气的 Anabantiform 鱼类的胃肠生理学和进食反应

湄公河三角洲是大量淡水物种的宿主，其中包括一组独特的兼性呼吸型 Anabantiforms。其中，条纹鳢（Channa striata）、攀鲈（Anabas testudineus）、巨型吻口鱼（Osphronemus goramy）和蛇皮吻口鱼（Trichogaster pectoralis）是越南水产养殖生产的主要贡献者。在这里，我们详细介绍了这四种物种对进食的胃肠道反应。蛇头的相对肠道长度最低，表明是肉食性的，而蛇皮的相对肠长是食草性的 5.5 倍；攀缘鲈鱼和巨型吻口鱼是中间的，表明是杂食性的。N-废物排泄（氨-N + 尿素-N）在食肉蛇头中最大，在食草蛇皮中最少，而净K + 排泄量则相反。同样，肉食性更强的物种比食草性更强的物种具有更高的胃酸。对水中酸碱通量的测量表明，最大的餐后碱性潮汐发生在蛇头鱼身上，而潜在的酸性潮汐则发生在蛇皮身上。其他令人感兴趣的发现是所有四种呼吸空气物种的肠道食糜中 PCO2（高达 40 mmHg）和（HCO3 -）（高达 33 mM）的高水平。使用攀缘鲈鱼的体外肠囊制剂，我们表明肠道对液体、Na+ 和 HCO3 - 的净吸收通过进食而上调，但不会通过净 Cl- 吸收、葡萄糖吸收或 K+ 分泌上调。HCO3 - 的净吸收上调表明高食糜 (HCO3 -) 不是由肠上皮分泌引起的。讨论了 PCO2 的通风控制以调节这些呼吸空气的鱼的餐后酸碱平衡的可能性。本文受版权保护。版权所有。