Molecular detection of Aeromonas hydrophila in the aquarium gold fish and cultured rainbow trout in Chaharmahal va Bakhtiary province

Aeromonas hydrophilia is the etiologic agent of motile aeromonas septicaemia, one of the most important bacterial diseases of fresh and marine water fishes. The aim of the present study was detection of A. hydrophilia in the aquarium goldfish and cultured rainbow trout in Chaharmahal va Bakhtiary province. In this study 50 goldfish from aquarium fish shops and 60 rainbow trouts suspected of having the disease from 6 farms (10 fish in each farm) were randomly collected. The average weight in goldfish and rainbow trout samples were 3-5 g and 10-20 g, respectively. Sampling was performed from kidney and liver, and inoculated into blood agar and incubated at 22°C for 24 hours. Pure colonies which are grown on the mediums were tested by catalase, oxidase and gram staining, then those of gram-negative, catalase and oxidase positive were diagnosed, and cultured on Shotts-Rimler medium (as selective medium for A. hydrophila). These mediums were incubated at 22 °C for 24-48 h. The typical colonies were tested by using oligonucleotide primers of lip gene by PCR method. In light of molecular analysis of all specimens, 9 and 6 isolates from rainbow trout and gold fishes were identified as A. hydrophila respectively. Due to the detection of A. hydrophila in both cultured rainbow trout and aquarium goldfish, the bacteria can lead to septicemia with mortality if the health management principles are not observed in fish farming.