Science, Tech, Math › Animals & Nature Learn All About Pinecone Fish Share Flipboard Email Print Ken Usami / Getty Images Animals & Nature Marine Life Marine Life Profiles Marine Habitat Profiles Sharks Key Terms Amphibians Birds Habitat Profiles Mammals Reptiles Wildlife Conservation Insects Forestry Dinosaurs Evolution View More By Jennifer Kennedy Marine Science Expert M.S., Resource Administration and Management, University of New Hampshire B.S., Natural Resources, Cornell University Jennifer Kennedy, M.S., is an environmental educator specializing in marine life. She serves as the executive director of the Blue Ocean Society for Marine Conservation. our editorial process Jennifer Kennedy Updated April 01, 2019 The pinecone fish (Monocentris japonica) is also known as the pineapple fish, knightfish, soldierfish, Japanese pineapple fish, and dick bride-groom fish. Its distinctive markings leave no doubt as to how it got the name pinecone or pineapple fish: it looks a bit like both and is easy to spot. Pinecone fish are classed in the Class Actinopterygii. This class is known as ray-finned fishes because their fins are supported by sturdy spines. Characteristics Pinecone fish grow to a maximum size of about 7 inches but are usually 4 to 5 inches in length. The pinecone fish is bright yellow in color with distinctive, black-outlined scales. They also have a black lower jaw and a small tail. Curiously, they have a light-producing organ on each side of their head. These are known as photophores, and they produce a symbiotic bacteria that makes the light visible.The light is produced by luminescent bacteria, and its function is not known. Some say that it may be used to improve vision, find prey, or communicate with other fish. Classification This is how the pinecone fish is scientifically classified: Kingdom: AnimaliaPhylum: ChordataClass: ActinopterygiiOrder: Beryciformes Family: Monocentridae Genus: Monocentris Species: japonica Habitat and Distribution The pinecone fish are found in the Indo-West Pacific Ocean, including in the Red Sea, around South Africa and Mauritius, Indonesia, Southern Japan, New Zealand, and Australia. They prefer areas with coral reefs, caves, and rocks. They are commonly found in waters between 65 to 656 feet (20 to 200 meters) deep. They may be found swimming together in schools. Fun Facts Here are a few more fun facts about the pinecone fish: It is popular in tropical aquariums because of its unique appearance. Despite that popularity, the pinecone fish is known to be hard to keep.They eat live brine shrimp and are more active at night. During the day, they tend to hide more.There are four species of pinecone fish: Monocentris japonica, Monocentris meozelanicus, Monocentris reedi, and Cleidopus gloriamaris. They are all members of the Family Monocentridae.They are usually a yellow or orange color with scales outlined in black. The fish are considered on the more expensive side, making them less common in home aquariums. Sources Bray, D. J.2011, Japanese Pineapplefish, , in Fishes of Australia. Accessed January 31, 2015.Monocentris japonicaMasuda, H., K. Amaoka, C. Araga, T. Uyeno and T. Yoshino, 1984. The fishes of the Japanese Archipelago. Vol. 1. Tokai University Press, Tokyo, Japan. 437 p., via FishBase. Accessed January 31, 2015. Mehen, B. Weird Fish of the Week: Pinecone Fish. Practical Fishkeeping. Accessed January 31, 2015.