Lumpsucker or lumpfish, Cyclopterus lumpus, eating salmon louses, Lepeophtheirus salmonis, from Atlantic salmon, Salmon salar, on salmon farm. Lumpfish is a species of cleaner fish, so called due to its natural behaviour removing and eating skin parasites from other species of fish.Sea lice are naturally occurring ectoparasitic copepods that attach themselves to marine fish and feed on mucus, skin and blood of their host. The salmon louse - Lepeophtheirus salmonis is of particular concern as it causes major health issues for farmed salmon including fin damage, skin erosion, wounds and a reduction in overall health and performance. If sea lice numbers are sufficient death can also occur. The treatment of them is currently dependent on a range of anti-parasitic chemical treatments, both bath and in-feed. The continued reliance and discharge of these chemicals combined with concerns about increasing resistance to their efficacy has led the salmon farming industry to introduce biological sea lice control with the use of cleaner fish that eat the sea lice from the salmons skin. Ballan wrasse and lumpfish are the predominant species used as cleaner fish, with a current heavy demand placed on wild capture fisheries to fulfil this demand despite the advent of farming for both species. Cleaner-fish, such as wrasse or lumpfish, live in the same cages as salmon where they attack and eat parasitic sea lice. generally have to be put into the cages in a ratio of 2 to 3 wrasses for 100 salmon. These cleaner fishes are used regularly to control sea lice on salmon farms in Scotland, Ireland and Norway.