Fishing activities on the lake of Longemer are managed by the Valley of the Lakes Fishing Company. The diversity of the habitats of the lake allows the presence of numerous fish. Among these species, the brown trout, the pike, and the river lota are the subjects of protective measures. The Amur Carp is, on the other hand, an Asian fish hatched illegally in lakes. Huge consumer of plants, it is used to fight against submerged aquatic vegetation. In Xonrupt-Longemer, it is suspected of destroying the last lake meadows.