This book, Polynesian Freshwater Fish and Crustaceans - Taxonomy, ecology, biology and management, valorises more than twenty years of research conducted in this region by the authors. There are about 89 species known from the brackish and freshwaters of the territory, i.e., 32 crustaceans (Decapods) and 57 fish. Among them, 7 are threatened and 23 are endemic to the area. The reader will find the main characteristics of the Polynesian Islands concerned with this guide (Cook Islands, French Polynesia, Niue, Pitcairn Islands, Tokelau, Tuvalu, Tonga, Samoa Islands, Wallis and Futuna), of the aquatic ecosystems and of the communities inhabiting them. The list of the present species, their adaptations to insular systems and the problems linked to their management and conservation are developed. In order to determine the different species, detailed identification keys are given, as are the main characteristics concerning their description, biology and distribution. Numerous photos and maps are also presented and complete the information given for each species. The handbook is primarily a didactic inter-disciplinary tool for the restitution of practical management actions that could readily be implemented by local communities and freshwater managers in relation to the management of threatened species. The information will however be of use to many other stakeholders especially those involved in education (teachers, NGOs, etc.). It has therefore been written in two different languages: French and English.