Insight on prevailing bacterial diseases affecting grass carp (Ctenopharyngodon idella)‎ at Aswan fish hatchery, Egypt

الملخص EN

Bacterial fish diseases are the major serious problems in the intensive-aquaculture due to naturally presence of their fish pathogens in the fish surrounding environment.

An epizootic was noticed in grass carp from El-Shalal fish hatchery, Aswan Governorate, Egypt during the induced spawning season (April & May, 2018).

Diseased fish showed hemorrhages all over the body, excess mucus on skin and gills and abdominal distension with congested gills.

The current study aims to spot light on the most predominant bacterial infections in the current hatchery, with special focus on biochemical characterization, molecular identification; as well as, pathogenicity, antimicrobial susceptibility and histopathological changes induced by the most prevalent isolated microbe.

Phenotypic and biochemical identification revealed prevalence of Aeromonas hydrophila (A.

hydrophila), Pseudomonas fluorescens (P.

fluorescens) and Enterococcus faecalis (E.

faecalis) with prevalence of (26%), (35%), and (14%) respectively.

P.

fluorescens, the most prevalent pathogen, was molecularly identified using the 16S rRNA gene in PCR technique and its pathogenicity was confirmed by experimental infection of grass carp as well as, the histopathological examination.

Antibiogramme test revealed that P.

fluorescens was sensitive to Ciprofloxacin, Cephalothin, Gentamicin and Amikacin and resistant to Cloxacillin, Penicillin, Erythromycin and Ampicillin._