Venomous fish stings are a common environment hazard worldwide. This study investigated the clinical effects and treatment of venomous fish stings. A prospective observational case series of patients presenting with venomous fish stings was conducted in tropical northern Australia. Twenty-two fish stings were included; subjects were 3 females and 19 males; mean age 35 (range 10-63). 9 by stingrays, 8 by catfish, 1 by a stonefish, 1 by a silver scat (Selenotocota multifasciata), and 3 by unknown fish. All patients had severe pain, but less commonly erythema, 3 cases (14%); swelling, 7 cases (33%); bleeding, 5 cases (24%); numbness, 4 cases (19%); and radiating pain, 3 cases (14%). Mild systemic effects occurred in one stingray injury. Treatment included hot water immersion, which was completely effective in 73% of cases, analgesia, wound exploration and prophylactic antibiotics. Stingray injuries should be explored and debrided with large wounds, while other stings only need appropriate cleaning. The routine use of antibiotics is not recommended.