Batfish, underwater vehicle designed to carry oceanographic instruments and sensors. It is towed behind a ship in a sawtooth, undulating pattern. The Batfish can dive or ascend by rotating its hydroplanes ("wings") on ship command, and is capable of diving between the surface and approximately 400 m. Control power, used to activate the wings, is derived from an impellor-driven hydraulic pump within the Batfish. The core of the armoured towing cable contains 7 electrical conductors through which electronic information is transmitted to the surface from sensors mounted on the Batfish. The information is transferred to a shipboard computer and stored on magnetic tape.

The Batfish was developed at the Bedford Institute of Oceanography, Dartmouth, NS, and manufactured by Guildline Instruments Ltd, Smiths Falls, Ontario. It is equipped with 3 sensors: a conductivity-temperature-depth probe, used to measure physical oceanographic features; a fluorometer (mounted atop the Batfish), measuring chlorophyll a fluorescence, the indicator of phytoplankton or plant biomass; and an electronic zooplankton counter (mounted below the Batfish), measuring small marine animals (approximately 0.5-4 mm long) which consume mainly marine plants. Information from the biological sensors is used in fisheries studies of the marine food chain.