Status of biofloc culture system in Sylhet, Bangladesh: Mass mortality of striped snakehead, Channa striata (Bloch 1793) due to coinfections with Aeromonas veronii and trematodes cercariae
Journal Title: Journal of Aquatic Research and Sustainability - Year 2025, Vol 2, Issue 1
Abstract
Biofloc aquaculture system is a modern culture technique known for its multiple benefits, including higher yield production, environmental sustainability and reduce production costs. However, its adoption in different regions faces many challenges, including frequent disease outbreak and system sustainability. The current study was aimed to evaluate the disease occurrence in biofloc fish farms of Sylhet district. Using a questionnaire-based approach, data were gathered from nine biofloc farms to identify prevalent diseases/signs and associated challenges. Our findings reveal that multiple disease and disease signs were commonly reported across farms, with each farm experiencing more than one disease. Tail rot emerged as the most widespread disease, affecting 55.56% of the observed cases. Additionally, all respondents (100%) emphasized persistent challenges with seed availability and electricity supply. Among the nine biofloc fish farms surveyed, farmers from seven farms considered biofloc as a non-sustainable (77.78%) culture system. Furthermore, we examined the incidence of significant mortality in striped snakehead fish (Channa striata) from a biofloc fish farming setup. Clinical and laboratory diagnostics were performed on the diseased specimens, revealing trematode cercariae infections on the skin of moribund fish, characterized by skin abrasions and red spots. The mortality pattern was acute and near about 80% of the culture stock were died due to this coinfections. Bacteriological analysis identified yellowish colonies on Rimler-Shotts (RS) selective media, indicative of Aeromonas spp. Polymerase chain reaction (PCR) targeting the 16S rRNA gene (1500 bp) and gene sequence results confirmed the bacterial species as A. veronii. The obtained sequences were analyzed using BLAST and subsequently submitted to the National Center for Biotechnology Information (NCBI) with the accession number ON854128. Antibiogram study disclosed that A. veronii were a multi-resistant pathogenic bacterium. Histopathological examination of the affected tissues revealed significant pathological alterations in the gills, liver, kidney, spleen, and muscles of the infected fish. The findings from the survey and lab-based diagnostics suggest that biofloc technology encounters several challenges, including input limitations and frequent disease outbreaks.
Authors and Affiliations
Anupoma Achariya, Shamima Nasren, Md. Siddikur Rahman Sujon, M. M. Mahbub Alam, Sarker Mohammed Ibrahim Khalil, Md. Abdullah Al Mamun
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Status of biofloc culture system in Sylhet, Bangladesh: Mass mortality of striped snakehead, Channa striata (Bloch 1793) due to coinfections with Aeromonas veronii and trematodes cercariae
Biofloc aquaculture system is a modern culture technique known for its multiple benefits, including higher yield production, environmental sustainability and reduce production costs. However, its adoption in different re...
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