A system (5, 10, 300, 310) for treating biomass includes a tarpaulin arrangement (10) fluidly coupled via a configuration of fluid-guiding pipes to control apparatus (300). Moreover, the tarpaulin arrangement (10) is adapted to be deployed and to enclose a net, enclosure or cage (80), and the tarpaulin arrangement (10) is provided with a plurality of floats (20, 30, 40, 50, 60, 70) disposed thereon so that selective adjustment of buoyancies of the floats (20, 30, 40, 50, 60) enables the tarpaulin arrangement (10) to adjust a volume of water present within the net, enclosure or cage (80) during treatment of the biomass. The biomass is optionally salmon fish, and the treatment if optionally de-licing of the salmon fish.
