Mass mortality of young striped jack Pseudocaranx dentex caused by a fungus Ochroconis humicola

Abstract

In April 2004, a fungal infection occurred in cultured young striped jack Pseudocaranx dentex at a fish farm in Ehime Prefecture, Japan. The cumulative mortality reached about 25% in one month after the disease was first recognized. Moribund fish showed disease signs such as abdominal swelling and distended kidney. A fungus was purely isolated from the kidney of the fish using PYGS agar. The colony was pale brown in color, and the conidia were two-celled, cylindrical to oblong with rounded ends and smooth-walled. From these morphological characteristics, the fungus was identified as Ochroconis humicola. This infection of marine fishes has been reported in the skin of juvenile fish, but not known in young fish. This paper describes the first case of O. humicola infection in visceral organs of young striped jack. © 2006 The Japanese Society of Fish Pathology.