Epitheliocystis Disease in Cultured Yellowtail Seriola mazatlana in Ecuador

Abstract.– Epitheliocystis, a disease of the gill and skin epithelial cells, is reported in the early developmental stages of Pacific yellowtail Seriola mazatlana , a new marine finfish species for aquaculture in Ecuador. Behavior, appearance of infected larvae and clinical signs of infection are described. Light microscopic and histological examinations confirm the presence of intracellular organisms in the gills, skin, nostril and buccal cavity. Proliferative cell response resulted in the gradual destruction of the functional integrity of the gills, causing massive mortalities.