Salmon Louse

The salmon louse is a small parasitic copepod that attaches to the skin of salmon and related fish in the Atlantic and Pacific oceans, feeding on its host's mucus, skin, and blood. After hatching, its larvae drift in open water as plankton until they find a fish to settle on, and heavy infestations can weaken or kill young or already stressed fish. It has become a major problem for salmon aquaculture, where dense pens of farmed fish allow infestations to build up and spread more readily than in the wild.