Dissect the gut free from the mesentary. Cut open the stomach and note any irregularities in the mucosal surface. Sample a small section of the stomach, as well as one or two pieces of intestine.

Also examine the contents of the gut and try and identify what the fish was eating.

In the video on the right, note that the intestinal contents may be examined for parasites, and the mucosal surface of the gut should be scraped for microscopic parasite evaluation as well.