Scatophagus argus of the family Scatophagidae inflicts painful wounds in fishermen during handling. The clinical picture is characterized by excruciating and persistent local pain disproportionate to the size of injury, redness, swelling and a throbbing sensation that extends to the limbs, followed by dizziness. The biological properties of the S. argus venom were studied to assess its risk and lethal factors with regard to human welfare. In contrast to other fish venoms, S. argus showed relatively low LD50 (9.8 mg/kg via i.p.). Haemolytic activity in human erythrocytes was recorded. Platelet lysis expressed as LDH activity of lysed cells was dose dependent. S. argus venom failed to induce any clot in human plasma. No PLA(2) activity was found in S. argus venom. Mild proteolytic activity was observed. The injection of venom in mice produced lesions and nociception, which were not inhibited by antihistamine pheniramine maleate, suggesting that histamine was not involved in the inflammatory process. The increase in serum creatine kinase activity indicated myotoxicity. Cytotoxicity on HeLa cells was observed. The spectrum of activity in experimental animals of S. argus crude venom resembles those of other fish venoms previously studied and well correlated to the systemic manifestations that are described for S. argus envenomation.