Methods for quantitative sampling of open marine and freshwaters are described, including fishing nets, plankton nets, pump samplers, the Patalas–Schindler volume sampler, and specialized methods for freshwater insects. Specialist methods for sampling freshwater floating, emergent, and submerged vegetation are described. Methods for quantitatively sampling the bottom fauna in the various substrates found in streams, rivers, lakes, and the sea bed are reviewed. The use of various poisons and anaesthetics for sampling fish are described.