The River Brent is an urban river flowing through northwest London, draining a heavily developed catchment of approximately 170 square kilometres across the London Boroughs of Barnet, Brent, Ealing, Harrow, and Hounslow before joining the Thames at Brentford. Despite its urban setting, the river supports a surprisingly diverse fish community, particularly in its upper and middle reaches where the channel takes on a more natural character. The river has a complex environmental history — high sewage levels had eliminated local trout populations at Brentford by the early 1920s, though the river was cleaned up by World War II and a few trout began returning in the 1990s. Today, the Brent offers accessible urban fishing with a range of coarse species, set against a backdrop of ongoing conservation and water quality challenges typical of heavily urbanised river systems.