maroon clownfish

Premnas biaculeatus, commonly known as spine-cheeked anemonefish or the maroon clownfish, is a species of anemonefish found in the Indo-Pacific from western Indonesia to Taiwan and the Great Barrier Reef. They can grow up to be about . 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 size-based dominance hierarchy; the female is largest, the breeding male is second largest, and the male nonbreeders get progressively smaller as the hierarchy descends. They exhibit protandry, meaning the breeding male changes to female if the sole breeding female dies, with the largest nonbreeder becoming the breeding male. The fish's natural diet includes algae and zooplankton. Description The characteristic that defines this genus is the spine on the cheek. The colors of the body and bars vary according to sex and geographic location. Despite the common name maroon clownfish, only some females have a maroon body color, with a range of color to dark brown. Juveniles and males are bright red-orange. The fish has three body bars which may be white, grey, or yellow. Where the female bars are grey, they can be "switched" rapidly to white if fish is provoked. The size-based dominance hierarchy means in any group of anemonefish, the female is always larger than the male. A significant difference in size is seen in this species, with females being one of the largest anemonefish, growing up to while males are much smaller, usually being . Color variations The significant color variations for fish in this species are related to sex and geographic location. Male and juvenile fish are bright red-orange which darkens on the fish changing to female, ranging from maroon to dark brown. The body bars of the female are narrower and the body bars reportedly all but disappear in older females. At least three geographic variations in the color of females are found, with fish from East Timor to Australia retaining white body bars. In the central Malay Archipelago, the head bar tends towards a dull yellow, with the other two body bars being grey. In Sumatra and Andaman Islands, all three body bars are yellow for both male and female, and the female body color can range from a dull maroon to a dark brown.