The aim of the present study was to determine the validity of behavior as an early sign of toxicity and respiratory injuries induced by acute exposure to cadmium in adult zebrafish (Danio rerio). The effects of three cadmium concentrations (35, 45, and 55 µg/L) on zebrafish behavior (i.e., general activity, exploratory/motor behavior, climbing to the water surface, tremors, and erratic movements) and gill histo...