Ectopleura larynx are small but “pushy” creatures – no more than a few centimetres in length. In the course of a few years, the species has evolved from living on rocks and ships’ hulls to being pests that prefer to settle on fish-farm seacages. In the high season, between August and October, farmers have to wash the nets every other week. As fish farms often have as many as ten cages, this absorbs a lot of resources. Scientists at SINTEF are carrying out trials by giving the hydroids a quick bath in hot water at various temperatures or using acetic acid to get rid of the creatures, and the acid has turned out to be very effective with the youngest individuals, even at the lowest concentration.