Lepidophagy is comparatively rare amongst teleost fishes, yet our understanding of this specialization is lacking. Therefore we examined the digestive tract features of Pachypterus khavalchor using morphological, osteological, histological and histochemical techniques to comprehend and relate structural organization of digestive tract with scale eating habit. Morphologically, the alimentary canal is defined by a short and muscular esophagus, well-developed stomach and comparatively short intestine. Gut content analysis and intestinal coefficient value (0.53 ± 0.01) revealed that P. khavalchor exhibit both carnivory and lepidophagy. However, P. khavalchor primarily feeds on the scales (67.47%) and other chitin-rich material like aquatic insects (17.62%), aquatic larvae (8.66%) which affirms its solid association with chitinase producing endosymbionts in the gut. Lepidophagy is further supported by the osteological observations. The perfect segregation of the functions such as food capture, ingestion and processing amongst the different types of teeth located in the oral cavity and pharyngeal region thus could be taken as evolutionary adaptations in scale eaters to support lepidophagy. Specialized arrangement of the esophageal and stomach epithelial folds could be altogether taken as an adaptation with the end goal to frame the scale stacks and accordingly facilitate the handling and processing of chitin-rich bolus. The esophageal mucosa is simple squamous epithelium instead of stratified epithelium with numerous goblet cells to withstand the mechanical harm by hard-food stuff like scales. The cardiac and fundic regions exhibited large number tubular gastric glands with simple columnar epithelium. Surface cells of all three stomach regions stained positive for PAS staining. The intestine is without pyloric caeca and is divided into anterior and posterior region. Histologically it is characterized by simple columnar epithelium with brush border and numerous goblet cells throughout its length. Presence of large number microvilli on anterior and posterior intestine was noticeable. Intestinal goblet cells reacted positively to PAS, AB (pH 1) and AB (pH 2.5). Secretions of goblet cells are important for lubricating and protecting the epithelium. The results of present investigation improve the understanding of the digestive physiology of scale eaters in general and P. khavalchor in particular. Overall, our data indicates that though P. khavalchor predominantly feeds on scale, the digestive physiology is adapted to support dual feeding habit (lepidophagy and carnivory).

中文翻译：

---

消化道的结构充足性支持cat鱼Pachypterus khavalchor（Siluriformes：Horabagridae）的双重进食习性。

硬骨鱼类在硬骨鱼中比较少见，但是我们对这种专业的了解却不足。因此，我们使用形态学，骨学，组织学和组织化学技术检查了哈氏白僵菌的消化道特征，以了解消化道的结构组织并将其与食性饮食习惯联系起来。从形态上讲，消化道的定义是食管短而肌肉发达，胃发达且肠相对短。肠含量分析和肠道系数值（0.53±0.01）表明，哈瓦克疟原虫同时具有肉食性和鳞状性。然而，卡瓦尔丘霉主要捕食鳞片（67.47％）和其他富含甲壳质的物质，例如水生昆虫（17.62％），水生幼虫（8。66％）证实其与肠道中产生几丁质酶的内共生菌牢固结合。骨科观察进一步支持了鳞状眼病。因此，在口腔和咽部区域的不同类型牙齿之间，食物的捕获，摄取和加工等功能的完美隔离可以作为食鳞动物的进化适应来支持鳞状细胞病。食道和胃上皮褶皱的特殊布置可以完全作为一种适应，最终目的是构筑鳞片堆叠，并因此促进富含甲壳质的丸剂的处理和加工。食道粘膜是简单的鳞状上皮，而不是具有大量杯状细胞的分层上皮，可以抵抗诸如鳞片之类的硬质食物的机械伤害。心脏和胃底区域表现出大量的管状胃腺和简单的柱状上皮。所有三个胃区域的表面细胞均对PAS染色呈阳性。肠无幽门盲肠，分为前区和后区。在组织学上，其特征是简单的柱状上皮具有刷状边界和在其整个长度上有许多杯状细胞。前后肠上均存在大量微绒毛。肠道杯状细胞与PAS，AB（pH 1）和AB（pH 2.5）呈阳性反应。杯状细胞的分泌对于润滑和保护上皮很重要。目前的调查结果提高了人们对一般食人鱼尤其是海龟的消化生理的理解。总体而言，我们的数据表明尽管P。