 The lesions typically occur on the elbows, knees and feet in swimming pool-related cases, and on the hands and fingers in aquarium owners.The inhibition of growth of "M. marinum" at 37 °C is related to its ability to infect the cooler parts of the body especially the extremities.Lesions appear after an incubation period of about 2–4 weeks, and after 3–5 weeks they are typically 1–2.5 cm in diameter.