Endoscopic Monitoring of Intestinal Parasites in the European Chub (Squalius cephalus).

Quantifying intestinal parasite load in freshwater fish requires the development of reliable, minimally invasive methods. We evaluated the use of a very thin and flexible endoscope to detect and quantify acanthocephalan parasites in 25 European chubs (Squalius cephalus). The presence and number of parasites, as estimated using the endoscope, were correlated with dissection-based counts, especially in the anterior part of the intestine accessible via the insertion tube. Accuracy declined in highly infected fish due to overlapping parasites, but endoscopy still provides an accurate evaluation of infection probability and intensity. Thus, this study validates the use of endoscopy as a reliable method for intestinal parasite monitoring in freshwater fish. The deployment of this tool for field-based studies offers promising perspectives for parasitology research.