Leave this to the professionals! While Crown of Thorns starfish (COTs) can naturally be found on the Great Barrier Reef, they aren't welcomed in large 'outbreak' numbers. They can decimate reefs very quickly when there's enough of them 😱 So, in response to saving corals and helping restore the balance of species, Master Reef Guides along with a team of specially trained crew, manually cull starfish using a lethal injection of either bile salts or household vinegar. Like what Master Reef Guide J