NOVELTY - An aerator (10) for a liquid medium, comprising: (a) a sealed drum (34) with a continuous side surface; (b) a stationary shaft; (c) several paddles (32) affixed to the exterior surface of the continuous side surface; (d) at least one floatation device; (e) a motor (36) and gearbox (38) for driving the drum; (f) a support frame for supporting the drum; and (g) a power supply for supplying power for driving the motor, is new.    USE - The aerator is used in fish farming and in waste water treatment facilities. It is also used in chemical or biological process such as waste water treatment of activated sludge and also in purification of drinking water using ozone.    ADVANTAGE - The rotation of the paddles through the liquid medium causes the liquid medium to be agitated and allows oxygen to be dissolved resulting in a higher concentration of dissolved oxygen for aerobic respiration that is desirable in fish farms and waste water treatment facilities. An increase in oxygen concentration results in an increase in the population of fish stock hence increased economic gains for fish farmers. The aerator is compact and supports a sealed large horsepower motor and gearbox system that needs less servicing and repairs than prior art external motor mounted aerators.    DETAILED DESCRIPTION - An aerator (10) or destratifier for a liquid medium, comprising:    (a) an environmentally sealed drum (34) having a first and second end and a continuous side surface between;    (b) a stationary shaft extending from the first and second ends;    (c) several paddles (32) affixed to the exterior surface of the continuous side surface of the drum;    (d) at least one floatation device;    (e) a motor (36) and gearbox (38) for driving the drum, mounted internally in the drum;    (f) a support frame for supporting the drum on the floatation device; and    (g) a power supply for supplying power for driving the motor, is new.    An INDEPENDENT CLAIM is also included for aerating or destratifying a liquid.    DESCRIPTION OF DRAWING(S) - The figure shows an isometric view of the liquid aerator.    Liquid aerator (10)    Perforated paddles (32)    Sealed drum (34)    Motor (36)    Gearbox (38)