The present invention relates to a system (2, 102) for removing exterior parasites from fish, such as salmon lice (5), which system comprises one or more mostly closed volumes or pools of seawater (6, 106), where fish are kept inside by boundaries, such as nets surrounding the volumes. The object of the pending patent application is to remove parasites such as salmon lice by a natural method. The objects can be fulfilled by letting the closed volume comprise a sub volume of fresh water (8, 108), which fresh water sub volume is connected to a supply of fresh water (10), which fresh water sub volume has an open access for fish to swim into the fresh water sub volume. Hereby, it can be achieved that parasites such as salmon lice which have fastening them-selves to the skin of salmon by a suction plate are removed by contact with fresh water. In addition, a system for effectively feeding fish kept in closed volumes or pools of seawater, where fish are kept inside by boundaries fish which results in reduced waste of fish feed and increased fish growth and further in reduced eutrophication of the surrounding sea.
