Graduate School of Informatics, Kyoto University, Yoshida-honmachi, Sakyo, Kyoto 606-8501, Japan,
Graduate School of Informatics, Kyoto University, Yoshida-honmachi, Sakyo, Kyoto 606-8501, Japan.
Zoolog Sci. 2020 Oct;37(5):444-449. doi: 10.2108/zs200047.
The Mekong giant catfish is one of the largest freshwater fish, measuring up to 3 m in total length. This study was designed to determine the feeding habits of to better understand how the fish achieve their large body size. We compared the relationship between gut length (GL) and total length (TL) among related species in superfamily Bagroidea, order Siluriformes ( and ) in the Kaeng Krachan reservoir, Thailand. The mean relative gut length (RGL = GL / TL) of was 3.50, showing that they have relatively long guts, with values more similar to those of omnivorous (RGL = 3.70) than to those of carnivorous (RGL = 0.92). In the allometric relationship (i.e., log GL = log + log TL), the slope close to 1 for ( = 1.07) has been widely observed in carnivores, while has a greater intercept of the linear equation than and , resulting in a similar GL of to omnivorous at approximately 35 cm in TL. Moreover, GL of at 150 to 250 cm in TL showed great variations (RGL = 1.35-6.32). The variation in RGL for seemed to result from a poor nutritional state. In conclusion, is suggested to feed on indigestible materials such as plants, algae, and sediments, and potentially experience fasting in a reservoir.
湄公巨鲶是世界上最大的淡水鱼之一，体长可达 3 米。本研究旨在确定湄公巨鲶的食性，以更好地了解这种鱼类如何实现其巨大的体型。我们比较了在泰国干拉洪水库的超科湄公河鲶形目鲶形目（ 和 ）的相关物种的肠长（GL）与全长（TL）之间的关系。湄公巨鲶的相对肠长（RGL=GL/TL）平均值为 3.50，表明它们的肠道相对较长，其值与杂食性的 （RGL=3.70）更相似，而与肉食性的 （RGL=0.92）不同。在异速生长关系（即 logGL=log+logTL）中，湄公巨鲶的斜率接近于 1（=1.07），这在肉食性鱼类中很常见，而 的线性方程的截距大于 和 ，因此在 TL 约为 35 厘米时，其 GL 与杂食性的 相似。此外，TL 在 150 至 250 厘米的湄公巨鲶的 GL 表现出很大的变化（RGL=1.35-6.32）。 的 RGL 变化似乎是由于营养状态不佳所致。总之，湄公巨鲶可能以不可消化的物质（如植物、藻类和沉积物）为食，并可能在水库中经历禁食。
