Systemic Mycobacteriosis along with Concurrent Fibroma in Goldfish, Carassius Auratus from India

Aim: Goldfish (Carassius auratus L.), a freshwater fish belonging to the family Cyprinidae, is an important ornamental fish species in the world. Herewith, we report a case of systemic mycobacteriosis along with concurrent fibroma in goldfish. Methodology: The protruding mass and internal organs exhibiting lesions were collected for histopathology and molecular diagnosis. The sections of cutaneous mass were stained with haematoxylin and eosin (H&E) and Masson trichrome, whereas sections from spleen as well as kidney were stained with H&E and Ziehl-Neelsen. For identifying the etiological agent, 16S rRNA gene fragment was amplified and sequenced, using genus-specific primers for Mycobacterium sp. Results: In histopathology, multiple granulomas could be observed in kidney and spleen sections. Importantly, typical acid-fast bacilli were demonstrated in granulomas in spleen. The sequence of 16S rRNA gene fragment amplified from spleen and kidney showed maximum similarity to Mycobacterium stomatepiae. Besides, the histopathological characteristics of the protruding mass were consistent with cutaneous fibroma. Interpretation: These findings assume significance as several Mycobacterium species, including the current one from ornamental fish are reported to be of zoonotic significance.