Premnas biaculeatus, commonly known as spine-cheeked anemonefish or the maroon clownfish, is a species of anemonefish that is found in the Indo-Pacific from western Indonesia to Taiwan and the Great Barrier Reef. They can grow up to be about 17 centimetres (6.7 in). Like all anemonefishes it forms a symbiotic mutualism with sea anemones and is unaffected by the stinging tentacles of the host anemone. It is a sequential hermaphrodite with a strict sized based dominance hierarchy: the female is largest, the breeding male is second largest, and the male non-breeders get progressively smaller as the hierarchy descends. They exhibit protandry, meaning the breeding male will change to female if the sole breeding female dies, with the largest non-breeder becomes the breeding male. The fish's natu