Meloxicam is a nonsteroidal anti-inflammatory drug with preferential cyclooxygenase-2 inhibitory activity. It is frequently used in veterinary medicine, including in fish species. The efficacy and safety of meloxicam, however, has not yet been reported in adult fish. The purpose of this study was to evaluate the acute toxicity of a single intramuscular injection of meloxicam in goldfish (Carassius auratus auratus). Following 3 wk of acclimation, 32 goldfish were randomly assigned to two groups of 16 individuals. Fish from the treatment group received a single intramuscular injection of 5 mg/kg meloxicam, while the fish from the control group received a single intramuscular injection of a 0.9% sodium chloride solution using a similar volume (1 ml/kg). No external lesions, mortality, or modifications in behavior or position in the water column were noted during the following 72 hr. Three days after the initial injection, all fish were euthanized by immersion in a solution of tricaine methanesulfonate. Complete postmortem and histologic evaluations were performed for each fish. Hemorrhage and muscular necrosis were observed at the site of injection in fish from both groups. Multiple granulomas of undetermined etiology were detected in numerous organs from fish of both groups. No statistically significant differences were detected in regard to the lesions observed in these two groups. This study demonstrates that a single intramuscular injection of meloxicam at a dosage of 5 mg/kg does not cause acute toxicity in goldfish.