Etiology of ulcerative lesions of Atlantic menhaden (Brevoortia tyrannus) from James River, Virginia.

We observed ulcerative lesions on live Atlantic menhaden, Brevoortia tyrannus, during ichthyofaunal sampling in the tidal James River in October 1999 (near Jamestown, VA, USA). Other synoptically collected fishes exhibited no signs of lesions or pre-ulcerative tissues. Live fish were classified as unremarkable (no dermal anomalies), pre-ulcerative (integument intact with boil-like swelling), and ulcerative (severe focal lesions). Specimens were analyzed for bacteria, fungi, and pathogenic protozoans including amphizoic amoebae, Pfiesteria piscicida, and Kudoa sp. No Pfiesteria were detected in any tissue specimen. All B. tyrannus examined, including tissues from unremarkable fish, tested positive for presence of the known fish parasite Kudoa. Only ulcerative lesions were also colonized by bacteria, fungi, and amphizoic amoebae. The absence of bacteria, fungi, and protozoans from unremarkable and pre-ulcerative fish suggests that association of other potential pathogens with B. tyrannus ulcers was due to secondary colonization following lesion formation as a result of Kudoa infection.