Greater siren are fish that can be caught on Molch island using the Cormorant's glove. Requiring 91 Fishing and 87 Hunter to catch, they provide 100 fishing experience and 130 hunter experience.
Before attempting to fish them, players must speak with Alry the Angler to obtain the Cormorant's glove. This item functions similarly to the Falconer's glove used in the hunter skill. Players must click on rapidly moving fishing spots and can obtain a variety of fish, including the Greater siren.
Greater siren require no bait to catch directly, however King worms are initially required to feed the cormorant. After caught, a knife can be used to cut the siren to obtain stackable Fish chunks which can be used as a substitute for the king worms. Cutting the fish provides 25 cooking experience.