The ornamental fish trade has experienced rapid global growth, with goldfish (Carassius auratus) being one of the most widely traded species. However, high-density stocking, poor water quality, and transportation stress often predispose ornamental fishes to various infectious diseases, threatening their health and economic value. In this study, 65 naturally infected goldfish were collected from multiple aquarium shops in Aurangabad, Maharashtra, and examined using a multi-tiered diagnostic protocol. Parasitological investigations included wet mount examinations of gills, skin scrapings, and blood smears, which revealed the presence of common ectoparasites and Endoparasites. Bacteriological studies, including Gram staining, acid-fast staining, and biochemical assays (oxidase, catalase, TSI, citrate, motility, and indole tests), led to the identification of multiple fish-pathogenic bacteria. Fungal pathogens, primarily Saprolegnia spp., were identified based on characteristic cottony mycelial growth on infected skin and fins and confirmed using lactophenol cotton blue staining. Histopathological analysis of gill, liver, kidney, and skin tissues revealed cellular degeneration, hyperplasia, necrosis, and inflammatory infiltrates, which correlated with the severity of the infection. The integrated diagnostic approach employed in this study highlights the importance of early detection and accurate identification of pathogens in improving disease management strategies for ornamental fish culture. These findings provide a critical reference for developing prophylactic and therapeutic interventions in the Indian ornamental fish sector.
Khan et al. (Sun,) studied this question.