nekton

noun

1. the aggregate of actively swimming aquatic organisms in a body of water, able to move independently of water currents.

noun

1. the population of free-swimming animals that inhabits the middle depths of a sea or lakeCompare plankton

1893, from German nekton (van Heusen, 1890), from Greek nekton, neuter of nektos “swimming,” from nekhein “to swim” (see natatorium).

1. The collection of marine and freshwater organisms that can swim freely and are generally independent of currents, ranging in size from microscopic organisms to whales. Compare benthos plankton.