Oomycete fungi associated with ulcerative mycosis in menhaden, <i>Brevoortia tyrannus</i> (Latrobe)

Abstract

Abstract. Deep necrotic ulcers in Atlantic menhaden, Brevoortia tyrannus (Latrobe), were consistently associated with the presence of oomycete fungi. These organisms were found in over 95% of all lesions both early and late. More than one species of fungus appears to be involved, indicating that these organisms are secondary to some other stressor. However, all characteristically elicit an atypical intense granulomatous inflammatory response and do not behave pathologically as typical oomycetes. Our observation that these fungi appear to be the only organisms consistently present in the earliest stages of the disease indicates that some non‐infectious stressor may be responsible for initiating the lesions and subsequently allowing the fungi to induce this atypical response.