Incidence of Photobacterium Damselae and Vibrio fluvialis in the Cichlid Fish, Pseudetroplus maculatus in Kannur District of Kerala, India

The study investigates the incidence of two pathogenic bacteria, Photobacterium damselae and Vibrio fluvialis, in Pseudetroplus maculatus, a commonly traded ornamental and edible cichlid fish. A total of 60 specimens of P. maculatus were collected from five different localities in Kannur District of Kerala, India; during January to April, 2024 and bacterial isolates were obtained using standard microbiological and molecular techniques. 16S rRNA gene sequencing confirmed the presence of both pathogens in significant proportion of samples. Phylogenetic tree also confirms the findings. Six out of 10 (60%) specimens collected from Chemballikkundu were positive for P. damselae and 8 out of 15 (53%) specimens collected from Kannapuram were positive for V. fluvialis. The results indicate that this fish, may serve as reservoir for pathogenic bacteria, potentially threatening both aquatic life and public health. Presence of these bacteria in the host fish indicates water pollution and poor water quality. Pathogenic Photobacterium sp. and Vibrio sp. could pose threat to the health of consumers through the ingestion of contaminated improperly cooked seafood or by swimming and other recreational activities in the contaminated water bodies. Photobacterium may gain entry to the human body during handling of contaminated fish through the cuts or abrasions also. The present findings emphasize the importance of microbial monitoring and hygienic handling practices in the fish trade.