The present invention relates to a device (1) for temperature adjustment of inflowing water to an at least partly submerged closed aquaculture cage (2). The device (1) is particular suitable for increasing the temperature in a sea based unit, where the inlet water has a lower temperature than the water surrounding the cage (2). The device (1) com prises a helical tube (20) circumferentially arranged around the outside of the cage (2), a water inlet (21, 23) to the tube (20), a water outlet (22) from the tube (20) into the cage (2) in the upper region of the cage (2), and a pump (30) for pumping the water through the tube (20).
