Introduction:

Pseudoplatystoma magdaleniatum, commonly known as striped catfish, is an endemic species of the Magdalena River basin, characterized by its large size and high commercial value. Given its critical endangerment due to overfishing, understanding its gastrointestinal tract morphology is crucial for conservation efforts and management in fish stocking programs.

Objective:

To characterize the morphology, histology, and histochemical qualities of the gastrointestinal tract of P. magdaleniatum, an endemic fish species in the Magdalena River basin, Colombia.

Methods:

Measurements of body height and weight of 22 captured adult individuals were taken, as well as of the organs comprising the digestive tract (esophagus, stomach, and intestine), and accessory and glandular organs (liver and gonads). Histological techniques, such as Hematoxylin and Eosin staining, were performed to characterize the organs structurally. Histochemical techniques were employed to describe the dynamics of mucins, and transmission electron microscopy was used.

Results:

The stomach and intestine exhibited four layers: mucosa, submucosa (absent in the esophagus), muscular, and serosa. The esophagus, with only three layers, was characterized by the presence of stratified squamous epithelium with goblet cells, club cells, and taste buds. Neutral mucins were detected along the esophagus, while acidic mucins were observed in the cranial and middle regions. The stomach featured a simple columnar epithelium with abundant gastric glands and exclusively neutral mucins. Finally, the intestine was characterized by a mucosal tunic of simple cylindrical epithelium composed of enterocytes and goblet cells, abundant folds, and the presence of sulfated and carboxylated neutral and acidic mucins.

Conclusions:

P. magdaleniatum exhibited a relatively short intestine for its size and weight. The histology of the gastrointestinal tract further supports adaptations for a protein-rich diet. These findings provide valuable insights for understanding the digestive physiology of this endangered species, which may inform conservation efforts and management strategies.