The problem of sea lice infestation of farmed salmon has become a major issue not only for the salmon farmers themselves but also for environmentalists, retails and consumers who are concerned about the effects the transfer of lice to wild populations of salmon and the effect that treatments to remove the lice may have on the environment and on the quality if the fish produced. Originally lice were treated with organophosphate pesticides and more recently with hydrogen peroxide, but the use of both these materials is now banned, leaving only one effective treatment, emamectin benzoate. However, there is now concern that lice are becoming resistant to this last effective treatment, so an alternative method of controlling the parasite is urgently needed. One solution that has been tried in recent years is biological control through the use of wrasse which can clean the lice off salmon, thus avoiding the need for any chemical treatments. Whilst this is ostensibly an ideal solution to the problem, the wild capture of the large numbers of wrasse that are needed by the salmon farming industry, has also come under attack from environmentalists, whilst farmers and regulators remain concerned about other diseases being transferred from the wild wrasse to the salmon. This project seeks to resolve all of the above issues by developing the technology for spawning and rearing the most promising cleaner fish, ballan wrasse, in captivity. This will allow large numbers of disease free fish to be produced both economically and sustainably. It will also look into the management of wrasse in salmon cages in order to achieve the effective removal of lice whilst at the same time safeguarding the health and welfare of the wrasse themselves. Achievements: Broodstocks of Ballan wrasse is successfully established in all three countries. Egg production and startfeeding the first Ballan wrasse larvae has been a success. Relatively high survival rates of Ballan wrasse juveniles are obtained in two of the partner countries.Products and services:Title: Technology to produce cleaner fish to control health threat sea lice in salmon New, environmentally friendly method for rearing of ballan wrasse, a cleaner fish that 'cleans' aquaculture salmon from sea lice, for the establishment of ballan wrasse rearing units in the Northern Periphery area to supply cleaner fish to the salmon farming industry.More information see: http://nppoutcomes.eu/Title: Manuals for the rearing of ballan wrasse and for maintaining wrasse health A series of technical leaflets that enable rearing and production of the cleaner fish ballan wrasse for salmon farmers and aquaculture producers wishing to embark on rearing wrasse.More information see: http://nppoutcomes.eu/