Radiographically Confirmed Vertebral Deformities in a Wild Schizothorax plagiostomus from the Lidder River, Kashmir Himalaya, India

Vertebral deformities are well documented in cultured fishes but remain poorly reported in wild populations, particularly in cold-water Himalayan taxa. Here, we report the first radiographically confirmed case of vertebral deformity in a wild Schizothorax plagiostomus (n = 1) collected from the Lidder River, a major tributary of the Jhelum River system, India. Digital radiography revealed multiple axial skeletal anomalies affecting distinct vertebral regions. Lordosis was observed in vertebrae V16–V26 within the precaudal (medial) region, while scoliosis extended from vertebrae V27–V33 across the precaudal and caudal regions. Ankylosis involving vertebrae V30–V33 resulted in partial fusion of caudal elements and an estimated 17% reduction in caudal peduncle length relative to morphologically normal conspecifics. To contextualize the deformity, morphometric comparisons were made with ten apparently normal individuals from the same population. Mean (± SD) values for standard length (235 ± 8 mm vs. 239 ± 6 mm), body depth (48 ± 3 mm vs. 52 ± 4 mm), and head length (62 ± 2 mm vs. 65 ± 3 mm) indicated measurable deviations in body proportions associated with the deformity. Twenty-one morphometric and five meristic characters were recorded following standard ichthyological protocols. Given the single-case design, no inferential statistics were applied. Although causality cannot be established, potential contributing factors, including nutritional stress, exposure to anthropogenic pollutants, and underlying genetic influences, are discussed in the context of Himalayan river systems experiencing increasing environmental pressure. This case highlights the utility of radiographic diagnostics for detecting sub-lethal skeletal anomalies in wild fishes and emphasizes the need for systematic monitoring. We recommend seasonal field surveys integrating radiographic screening, morphometric assessment, and environmental DNA–based assays targeting metal-associated biomarkers to establish baseline prevalence and evaluate potential environmental drivers of skeletal deformities in wild cold-water fishes.