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Diseases of Aquatic Organisms

    DAO prepress abstract   -  DOI: https://doi.org/10.3354/dao03720

    First report of Achlya bisexualis infection in captive-reared endangered golden mahseer Tor putitora

    Victoria Chanu Khangembam*, Dimpal Thakuria, Vinita Pant, Ritesh Shantilal Tandel, Bipin K. Vishwakarma, Nityanand Pandey, Amit Pande, Pramod Kumar Pandey

    *Corresponding author:

    ABSTRACT: Achlya bisexualis is a notorious oomycete pathogen with the potential to cause emerging disease in fish farms. In this study, we report the first isolation of A. bisexualis from captive reared golden mahseer Tor putitora, a critically endangered fish species. The infected fish show a cotton-like growth of mycelia at the site of infection. The mycelium when cultured on potato dextrose agar produced radially growing white hyphae. The hyphae were non-septate and some of them carried matured zoosporangium with dense contents. Spherical gemmae with stout stalks were also observed. All the isolates had 100% identity in ITS-rDNA sequence and showed highest similarity to that of A. bisexualis. In molecular phylogeny, all the isolates formed a monophyletic group with A. bisexualis which was supported by a bootstrap value of 99%. Based on the molecular and morphological findings, all the isolates were confirmed as A. bisexualis. Further, the anti-oomycete effect of boric acid, a known antifungal agent, against the isolate was evaluated. The minimum inhibitory concentration and minimum fungicidal concentration were found to be 1.25 g l-1 and >2.5g l-1 respectively. Isolation of A. bisexualis from a new fish species indicates its possible occurrence in other unreported hosts. Considering its wide infectivity and the potential to cause disease in farmed fishes, its probable prevalence in a new environment and host needs to be closely monitored to prevent the spread of infection, if any, by adopting suitable control measures.