The sympathoadrenal system plays an essential role in forming the body’s response to the action of stimuli of various natures and intensities. The content of deposited catecholamines in peripheral blood erythrocytes is one of the most accessible parameters for an adequate description of the functional activity of the sympathoadrenal system in humans and rats. The aim of the work is to assess the accumulation of catecholamines in erythrocytes of sea ruffs Scorpaena porcus L. at various pollution levels in the bays of Sevastopol. The phenomenon of accumulation of catecholamines in erythrocytes of the peripheral blood of fish is revealed. The concentration of erythrocytes with deposited catecholamines was higher in fish from polluted bays. In 2006, fish from Alexander Bay exhibited a significantly higher erythrocyte content of deposited catecholamines (36.04%) compared to those from the background area (28.19%) and Quarantine Bay (30.74%) (P < 0.01). Similar levels were observed between Quarantine Bay and the coast of Balaklava. In 2007, fish from Alexander Bay maintained a high erythrocyte catecholamine content (35.2%), while those from Quarantine Bay exhibited a lower level (23.8%) (P ≤ 0.01). In 2008, the erythrocyte catecholamine content in Quarantine Bay was six times higher than that observed in fish from Martynov Bay. These findings underscore the variability in catecholamine concentrations among fish populations inhabiting different coastal regions, suggesting potential environmental influences on stress responses..