This report describe the relationships between the timing and magnitude of freshwater flows in the Pangani system and the biology and life history characteristics of its key fish and invertebrate species. Such information could be used to infer what the historic abundance levels and distribution patterns were for these species in the Pangani catchment (where such information is lacking); predict how abundance and distribution patterns may change in the future under altered flow patterns; and derive the relationships between water level and fishery production that will be used to predict changes in catches in Nyumba ya Mungu, Lake Jipe, Kalimawe Dam and the Pangani estuary under different flow and water-level scenarios. This report is the product of two, short, desk-based Specialist Studies of the Pangani River Basin Flow Assessment (PRBFA) Initiative. Based on published literature, information from the Internet and from a five-day field visit in June 2007, the report describes the main aquatic biotopes of the Pangani River Basin, an area of over 43,000 km².