A method for taking fish up from a body of water comprising the steps of providing a duct (14) having a lower open end below the water surface and an upper open end arranged at a floating working platform (5) above sea level introducing water into the duct (14) from the upper open end to give a water stream from the upper open end of the duct to the lower open end of the duct and allowing the fish to swim up in the duct against the water stream therein. The incoming water is directed to flow into the duct, and the fish is separated from the flowing by means of a grating (16) inclining upwards from the top end of the duct to a separation plate (17) arranged above the water level in the duct. A device for taking up fish, using the mentioned method is also described.