Simultaneous multiple ectoparasitic infection in cultured Goldfish (Carassius auratus) associated with environmental conditions and management – Multiple parasitism in goldfish

Resumo (EN)

Parasitic infections of fish are common and often debilitating the host, but multiple and simultaneous parasitism is rarely found. Its occurrence is usually associated with environmental and management issues. In this study, we describe the prevalence of multiple and concurrent parasitic infections in goldfish (Carassius auratus) raised in fish farms. Fish with skin damage (nodules and ulceration) were subjected to necropsy and examinations with fresh scraped of skin and gills, histopathological examination with HE and Giemsa stain, ultrastructural study by transmission and scanning electron microscopy. We identified in the skin the multiple parasitic infection by Gyrodactylidae, Epystilis sp., Vorticella sp., Trichodina sp., Ichthyophthirius multifilis, Tetrahymena sp. and Ichthyobodo necatrix associated with epithelial cell hyperplasia and epidermal sloughing. Although no gross lesions were observed in the gills, we identify a large number of parasites (Gyrodactylidae, Piscinoodinium sp., Ichthyophthirius multifilis, Vorticella sp. and Trichodina sp.) and microscopic lesions such as epithelial hypertrophy and hyperplasia, fusion of secondary lamellae, leukocyte infiltration, epithelial cells detachment, resulting in respiratory distress. In conclusion, multiple and simultaneous parasitism was very prevalent in goldfish with skin lesions, usually associated with ciliates and flagellate protozoan and it was associated with adverse environmental conditions and inadequate management.