Q: Anyone who has cleaned and examined the stomach contents of a wahoo has come across one of these critters. The wahoo I cleaned recently had two of them. What are they and how do they live in a harsh environment like the digestive tract of a fish? Are they harmful to the fish? And how does a pelagic fish like a wahoo encounter an internal parasite to begin with? - Scott Kerrigan, Wilton Manors, FloridaA: These are "giant stomach worms" of the genus Hirudinella, which reach sizes up to 8 inches long. I have seen them also in the stomachs of tunas caught in the Gulf of Mexico. Read More