Scoliosis deformity in Alburnus escherichii, an endemic freshwater leuciscid (Teleostei) from the Sakarya River Basin, Türkiye: Morphological description and a case study

In this study, a total of eight Alburnus escherichii individuals were captured from the Sakarya River Basin, Türkiye. In only one of these specimens, a skeletal deformity (scoliosis) was observed and examined. The scoliosis affected the caudal region of the vertebral column, presenting two curves originating posterior to the dorsal fin. These curves formed two angles, measuring 135° and 152°. Externally, at the point of scoliosis onset, the body contour and lateral line scales were deformed. The deformity affected the posterior part of the dorsal fin and the anterior part of the anal fin. Additionally, the neural and hemal spines of the ultimate abdominal vertebra were slightly deformed. This study discusses the possible causes of scoliosis and the significance of reporting such deformities for anatomical and broader ichthyological research.