Pseudotylosurus microps is a medium-sized species commonly known as needlefish. It is
distributed in the Amazon and Paraná River basins. This piscivorous species lacks a well-
defined stomach, is solitary, and swift, exhibiting epipelagic habits. The objective of this study
was to describe the anatomy and histology of the digestive tract, aiming to contribute to the
understanding of its morphology and function. The external and internal morphology of the
digestive tract was observed, including the position of the mouth, oral dentition, tongue,
pharynx, gill arches, stomach shape, esophagus, and intestines. Histological characterization
was achieved using hematoxylin and eosin-stained histological sections. The results revealed
that the digestive system of P. microps is a hollow tube composed of the esophagus and
intestine, without a well-defined stomach. The esophagus is lined with stratified squamous
epithelium and a muscular layer that extends throughout its length. The morphohistology of the
intestine differs in the middle and posterior parts. In the middle section, four layers—mucosa,
submucosa, muscular, and serosa—were observed, along with gland-like structures resembling
Lieberkühn's crypts and villi lined with simple columnar epithelium, featuring goblet cells and
microvilli. The posterior intestine (rectum) consists of columnar epithelium with a higher
abundance of goblet cells. The digestive tract of P. microps aligns with its piscivorous feeding
habits, displaying histological features that reflect adaptation to the absence of a stomach.
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