Alloglossidium corti is a digenean trematode, with a 3-host life cycle, involving mollusks and crustaceans as intermediate hosts and fishes as the final host, in which egg production takes place Its most frequent hosts are catfishes, including Ameiurus catus (White Catfish), A. melas (Black Bullhead), A. natalis (Yellow Bullhead), A. nebulosus (Brown Bullhead),I ctalurus punctatus, (Channel Catfish), and Noturus spp. (Madtoms). The parasite and its hosts are native to rivers in the midwestern and southeastern US. Alloglossidium corti was found in White Catfish in the Sacramento-San Joaquin Delta in 1966-67 (Hensley and Edwards 1968). White Catfish are native to Atlantic drainages of the southeastern United States,and were introduced to the San Francisco Bay and Columbia River waterseds in the 1970s.