Abstract
Freshwater fish are often exposed to threats from anthropogenic or natural origins, such as pathogenic or opportunistic microorganisms responsible for a broad range of severe infections. In this study, we aimed to assess this microbiological threat to fish in an Algerian northwestern dam Sekkak (Tlemcen) by evaluating the diversity of ichtyopathogenic bacteria. In order to determine the water quality, physicochemical analyses of the dam water were carried out in situ. Ichtyopathogenic bacteria were isolated on selective media and identified by API galleries and molecular techniques (PCR and sequencing of the 16S rRNA gene). Besides, the antibiograms were constructed for all the isolates. The physicochemical and bacteriological analyses allowed us to classify the dam water as moderately polluted to polluted. Furthermore, an important diversity of ichtyopathogenic bacterial species was observed as Aeromonas hydrophila, Providencia rettgeri, and Pseudomonas aeruginosa were retrieved. The antibiogram test revealed notable resistance. The antibiotic family for which most resistances were found was the β-lactam family, followed by aminoglycosides and macrolides. These results indicate that aquatic environments can shelter multidrug-resistant pathogenic bacteria representing a threat to the endemic fauna. Therefore, it is important to closely monitor these waters in order to improve the fish's living environment and ensure healthier production.