This publication provides a series of keys to the early stages of "Coarse Fishes" that occur in British fresh waters. During the first month of free existence, these fishes develop through a number of stages that are difficult for aquatic biologists (and most ichthyologists) to recognise. This difficulty in distinguishing one species from another has led to considerable neglect of these early stages and their impact on the surrounding biota as predators, competitors and prey. Until recently, studies on recruitment in these early stages were also few and far between. This series of keys provides a most necessary tool to assist such studies. It comprises keys to five developmental stages of coarse fish: free embryos, young larvae, intermediate larvae, older larvae and young juveniles. Clearly illustrated with line-drawings and colour photographs, it also includes notes on the collection, preparation and preservation of material.