Learn All About Pinecone Fish

Pinecone fish (Monocentris japonica), side view
Ken Usami / Getty Images

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. 


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.


This is how the pinecone fish is scientifically classified:

  • Kingdom: Animalia
  • Phylum: Chordata
  • Class: Actinopterygii
  • Order: 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.


  • Bray, D. J.2011, Japanese Pineapplefish, , in Fishes of Australia. Accessed January 31, 2015.Monocentris japonica
  • Masuda, 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. 
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Kennedy, Jennifer. "Learn All About Pinecone Fish." ThoughtCo, Aug. 27, 2020, thoughtco.com/pinecone-fish-profile-2291572. Kennedy, Jennifer. (2020, August 27). Learn All About Pinecone Fish. Retrieved from https://www.thoughtco.com/pinecone-fish-profile-2291572 Kennedy, Jennifer. "Learn All About Pinecone Fish." ThoughtCo. https://www.thoughtco.com/pinecone-fish-profile-2291572 (accessed December 4, 2022).

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