A general investigation was carried out on Lake Liambezi to characterize the limnological features of the lake. The lake, 101 km² in area and situated within the tropics, was found to be shallow and bordered by reed swamps, particularly on the south-western shore. It was polymictic and consequently oxygen levels were high at all depths. Transparency was such that photosynthesis occurred to the bottom. Conductivity ranged from 17,3 to 41,2 mSm⁻¹ and the waters were moderately alkaline. Transfer of organic detritus from the reed swamp into the open water has resulted in the presence of high levels of organic nitrogen and phosphorus whilst ambient levels of inorganic forms were low. Planktonic chlorophyll a concentrations ranged between 1 and 104 μg l⁻¹ and Microcystis was the dominant phytoplankter. The dominant zooplankter was Bosmina. The important species of phytoplankton and zooplankton are listed and include two new species of blue-green algae which are described. The lake was found to be generally similar to most shallow tropical African lakes with a wide diversity of food sources for fish. Progressive encroachment by Salvinia appears to hamper access to fishing areas and the fishery potential is threatened. Keywords: Shallow tropical lake, limnology, water quality, biological characteristics, phytoplankton, zooplankton, Gloecapsa laeta sp. nov., Spirulina liambeziensis sp. nov., Salvinia infestations.