Background: Ornamental fishkeeping is a widely embraced hobby globally. In India, Kolathur, Chennai Tamil Nadu is an important ornamental fish hub involved in trading of ornamental fishes. As a lucrative industry, the ornamental fish trade faces significant challenges due to diseases caused by various pathogens, impacting market value and causing economic losses.&nbsp; 
 
Methods: A surveillance study was conducted in Kolathur, Chennai, from December 2022 to August 2023. Ornamental fish samples exhibiting clinical signs of bacterial diseases were collected from the farms and retail outlets. Bacterial isolation and identification techniques, including conventional and PCR detection, were employed to isolate and identify bacterial strains from infected fish samples. 
 
Result: Out of 196 fish samples, 51 (29.4%) were found infected with bacterial pathogens. The prevalent bacterial pathogens included Aeromonas veronii (47%), A.caviae (17%), Pseudomonas aeruginosa (15%), Streptococcus sp. (11.3%), Mycobacterium fortuitum (5.6%) and Shewanella sp. (3.7%). Different fish families exhibited varying susceptibility to bacterial diseases, with cyprinids being the most affected (56.6%). The findings stress the importance of adhering to health regulations to prevent transboundary spread and suggest the development of targeted management strategies to sustain the health of ornamental fish populations.

Prevalence of Bacterial Diseases in Ornamental Fish Rearing Units of Kolathur, Tamil Nadu, India