A trout can look and focus out of both corners of each eye simultaneously, meaning that it can see in almost every direction at once. There is far more genetic variation in British wild brown trout than between any human populations on the planet. Trout can live for up to 20 years, but few make it past year one. Trout get darker when being aggressive, lighter when being submissive. Introduced brown trout have been naturalised in Australia, New Zealand, the USA, Canada, Sri Lanka, South Africa, Zimbabwe, Malawi, Kenya, Kashmir, Bhutan, the Falkland, Chile and Argentina.