Artemia Hatchery easy to use. Put about 200 ml Saltwater in the box below the upper edge of the ring. Put some Artemia eggs on the water surface within the ring. Put the lid on. After 24 hours the brine shrimp start to hatch and sink down in the ring. Attracted by the light through the opening of the lid, they swim through the gap beyond the ring to the opening of the lid, where they can be sucked in with an eye dropper and fed to the fish.