Neobenedenia girellae (Monogenea) infection of cultured cobia Rachycentron canadum in Taiwan

A benedeniid parasite infecting the body surface of cobia Rachycentron canadum cultured in net cages in Taiwan was identified as Neobenedenia girellae. This is the first confirmed case of N. girellae infection of marine fish from Taiwan. N. girellae was not randomly distributed on the host; it concentrated on the dorsal side of the head area (59.7%), especially on the eyes (23.7%), while it was less frequent on the ventral side and not detected on the fins. N. girellae caused considerable histological damage to the host through the attachment by the haptor and possibly through feeding activity by the pharynx. In infected eyes, epithelial cells of the cornea were often partially lost, and the collagenous stroma was considerably thickened and edematous, associated with massive inflammatory cell infiltration.