Histopathological Changes in Gills, Liver, and Kidney Tissues of Bighead Carp (Aristichthys nobilis) Due to the Effects of Acute High-Temperature Stress

Histopathological evaluation of fish tissues is a reliable method for detecting exposure to toxins and other environmental perturbations that cause stress or even death. This study aimed to evaluate the histopathological changes that might occur in the internal organs of Bighead carp (Aristichthys nobilis) following acute high-temperature stress. By examining tissues sampled at various timepoints after heat shock (3, 6, 12, and 24 hours), we observed severe anatomical alterations in three vital organs. In the gills, epithelial lifting and edema, blood congestion, primary lamellae thickening, and secondary lamellae curling, shortening, and fusion were evident. In the liver, karyolysis, necrosis, hyperemia, dilation of sinusoids, nuclear hypertrophy, and congestion of the central vein were observed. Kidneys displayed dilation of the Bowman’s space, an increase in the diameter of the renal tubules, hyperemia, shrinkage and congestion of the glomeruli, and tubular necrosis. Cumultaively, this analysis indicates that Bighead carp are highly susceptible to changes in environmental temperature, and rapid intervention is required in response to temperature disruptions during aquaculture. This study will therefore encourage aquaculturists to closely monitor culture temperatures for this economically important species of fish.