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Purpose: Henneguya sp. is a crucial myxosporean parasite known to cause milky flesh or tapioca disease in the freshwater fish population, leading to heavy mortality. Studies to investigate its host range and to monitor their prevalence in wild and aquacultured fish are necessary., Methods: The infected orange-spotted snakehead (Channa aurantimaculata) fish samples showing clinical signs such as severe ulceration and open wounds on the mouth and operculum were collected from an ornamental fish-rearing unit in Chennai, Tamil Nadu. The sample was diagnosed with myxosporean infection by microscopic observation, morphological records and DNA sequencing followed by phylogenetic analysis., Results: The Henneguya infection was identified in C. aurantimaculata for the first time. Necropsy of the infected fish revealed characteristic multifocal whitish-yellow, oval-shaped cysts measuring 3-5 mm in length on the liver and spleen. The wet mount of cysts showed numerous mature Henneguya spores that were uninucleate, elongated, lenticular and ellipsoidal with the bluntly rounded anterior end gradually tapering off to the posterior with a caudal elongation. The spore body measured 12.1 ± 0.9 μm (10.1-14.7 μm) × 7.1 ± 0.6 μm (5.3-8.5 μm) with two slightly unequal pyriform polar capsules of 6.1 ± 0.5 μm (5.1-7.4 )× 2.5 ± 0.4 μm (1.6-3.9) (large); 6.0 ± 0.4 μm (5.2-6.4) × 2.5 ± 0.3 μm (1.7-3.1) (small) and a caudal elongation of 16.1 ± 1.2 μm in length. The parasite was confirmed to be a Henneguya sp. by PCR amplification of SSrRNA followed by gene sequencing. The sequence generated was submitted in the GenBank under accession number PP852214.1 The maximum likelihood analysis revealed that the obtained sequence is a close relative of H. exilis with pairwise sequence variation of 3.3% and a homology of 99.04%., Conclusion: The findings highlight the potential impact of Henneguya sp. on ornamental fish health, underscoring the need for vigilant monitoring and management in India., Competing Interests: Declarations. Ethical Approval: Ethical approval for this study was given by the Institutional Ethics Committee at the Dr. M.G.R. Fisheries College and Research Institute, Ponneri, Tamil Nadu. All research activities adhered to ethical guidelines of CPCSEA (Committee for the Purpose of Control and Supervision of Experiments on Animals) for experimentation on fish, 2021. Inform Consent: “All authors have read, understood, and have complied as applicable with the statement on “Ethical responsibilities of Authors” as found in the Instructions for Authors and are aware that with minor exceptions, no changes can be made to authorship once the paper is submitted.” Consent to Participate: Not applicable. Consent to Publish: Not applicable. Competing Interests: The authors declare no competing interests., (© 2024. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)