Swim Bladder Disorders in Koi Carp (Cyprinus carpio)
Department of Veterinary Medical Sciences—Alma Mater Studiorum University of Bologna, 40064 Bologna, Italy
DAP Tim Barbe and an der Steenstraat 45, 1750 Lennik (Vlaams-Brabant), Belgium
Author to whom correspondence should be addressed.
Received: 22 September 2020 / Revised: 21 October 2020 / Accepted: 26 October 2020 / Published: 28 October 2020
Physostomous fish like cyprinids possess a swim bladder with a pneumatic duct in connection with the foregut, permitting the gas to enter into or be released through the alimentary canal. Due to this peculiar anatomic structure, bacteria and mycetes can potentially ascend the duct and colonize the swim-bladder. Besides inflammatory reactions, other swim bladder disorders include fluid accumulation, collapse, overinflation, and herniation. These swim bladder disorders and consequent buoyancy problems can be encountered in ornamental fish. Nonetheless, details about comprehensive disease management are poorly represented in the koi carp (Cyprinus carpio) literature. A clinical–pathological and microbiological investigation was performed in nine koi carp presenting abdominal swelling and abnormal swimming behavior. Swim bladder deformation, accumulation of clear fluid within the swim bladder, chronic aerocystitis, and bacteria identified as Aeromonas hydrophila/caviae group and Shewanella xiamenensis were the main findings. A wide range of sensitivity was shown to antimicrobials for isolated S. xiamemensis strains. Accordingly, antibiotic treatment succeeded in the full recovery of three cases in which S. xiamemensis infection was detected. Along with these results, the contribution of this study to the scientific field is to document a multidisciplinary clinical–pathological and microbiological investigation of these animals, which are rightly considered pets and should be similarly approached.