Isolation and Molecular Identification of Bacterial Gills Pathogen Isolated from Cultured Common Carp Cyprinus carpio (L.) in Earthen Ponds in Basrah Governorate, Iraq

Fifteen common carp samples were collected from a three fish farms infected with bacterial gill disease in an epidemic manner in order to identify the causative bacterial pathogens. Bacterial gill disease was studied in farmed common carp in Basrah Governorate, Iraq. The pathological signs related to fish behaviour and gross damage in gill tissues were recorded. The pathogens of bacterial gill disease were diagnosed using VITEK 2 technique after isolation and purification of bacteria on suitable culture media and the diagnosis was confirmed genetically using 16s RNA technique. The results included recording two species of bacterial pathogens, namely Aeromonas sobria and Sphingomonas paucimobilis are isolated from all collected fish. A. sobria recorded in NCBI under ID: OR122346.1, while two isolated S. paucimobilis was under ID: OR121489.1 and OR128365.1 respectively. The obtained findings indicated that the causative bacterial pathogens were variable along with the variability of location and time the environment was the same, so this variation will cause the change in the species or strains causing the disease.