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The hemorrhagic disease has become a major bottleneck in yellow catfish Pelteobagrus fulvidraco aquaculture. Yet scarce information is available on Bacillus subtilis as a pathogen of hemorrhagic disease in cultured yellow catfish. In this study, a virulent isolate, temporarily named HS5, was isolated from hemorrhagic disease-infected cultured yellow catfish, and was identified phenotypically and molecularly as B. subtilis. In addition, isolate HS5 showed an LD50 value of 5.20×106 CFU/ml in yellow catfish, exhibited beta-haemolytic activity, harbored the virulent entFM gene, and displayed high susceptibility to enrofloxacin and florfenicol in aquaculture use. To the best of our knowledge, this is the first report of B. subtilis as a pathogen of hemorrhagic disease in farmed yellow catfish.

Enteritis is known as a major disease in snakehead fish Ophiocephalus argus aquaculture and has resulted in large economic losses. Yet only scarce information is available on Aeromonas veronii as a causal agent for enteritis in O. argus. In this study, a virulent strain, temporarily named HY2, was isolated from diseased snakehead fish suffering from enteritis, and was identified as A. veronii through molecular and phenotypic methods. In addition, the HY2 isolate showed an LD50 value of 2.8×105 CFU mL-1, and was highly sensitive to aminoglycosides, macrolides, polypeptides, quinolones, sulfonamides and tetracyclines antibiotics. To the best of our knowledge, this is the first report of A. veronii as a potential pathogen of enteritis in snakehead fish.

Enteritis has resulted in large economic losses in channel catfish aquaculture. Yet only scarce information is available on Plesiomonas shigelloides as a causal agent for this disease. In this study, a virulent strain, temporarily named BD1, was isolated from diseased channel catfish suffering from enteritis, and was identified as P. shigelloides through molecular and phenotypic methods. A phylogenetic tree was also constructed to determine its taxonomic position. In addition, the BD1 isolate has developed multiple resistances to aminoglycosides, amphenicols, quinolones, tetracyclines and sulfonamides drugs for veterinary uses in aquaculture as revealed when screened against a range of common antibiotics. To the best of our knowledge, this is the first report of P. shigelloides as a potential pathogen of enteritis in channel catfish.

Bacteriosis has caused significant economic losses in farmed yellow catfish Pelteobagrus fulvidraco. Information is limited on Shewanella putrefaciens as a pathogen for yellow catfish. In this study, a virulent strain, temporarily named Y2, was isolated from diseased yellow catfish, identified phenotypically and molecularly as S. putrefaciens. A phylogenetic tree was constructed to examine isolate Y2 and compare it to other known isolates. In addition, isolate Y2 is apparently susceptible to aminoglycosides and tetracycline drugs for veterinary use in aquaculture as revealed when screened against a range of common antibiotics. To the best of our knowledge, this is the first report of S. putrefaciens as an emerging pathogen for cultured yellow catfish.

Bacteriosis is a major economic problem affecting the farming industry of whiteleg shrimp Penaeus vannamei. Little information is available on Providencia rettgeri as a possible pathogen for P. vannamei. In this study, a virulent strain, here named S6, was isolated from diseased P. vannamei, identified phenotypically, and molecularly, as P. rettgeri. A phylogenetic tree was constructed to examine the taxonomic position and relatedness of isolate S6 to other P. rettgeri isolates. When screened against a range of common veterinary antibiotics, isolate S6 exhibited resistance to aminoglycosides and sulfonamides antibiotics in aquaculture. To the best of our knowledge, this is the first report of P. rettgeri as a causal agent of bacteriosis in freshwater farmed P. vannamei.