Pinecone Fish

When most people think of bioluminescence, they tend to think of some of the fearsome denizens of the deep such as the Anglerfish and its famous dangling luminescent “lure”. However, this dazzling phenomenon can also be found in fish that live in shallower waters.

A good example of this is the monocentrid Pinecone Fish (Cleidopus gloriamaris) which lives in the tropical and sub-tropical waters of the Indian and Pacific oceans. Growing to around 6.4 inches long, its body has a striking pinecone pattern made by a covering of large, bony plate-like scales that provide a measure of protection.

All pinecone fish have bioluminescent patches on either side of their lower lip that they use to locate and attract the plankton on which they feed at night. The light is not generated by the fish itself but by a symbiotic group of bioluminescent bacteria that live in a special organ called a photophore. The colour of the light varies depending on the amount of light reaching it, and while it can’t turn the glow on and off at will, the pinecone fish can hide it by simply tucking its lower lip under its upper one when it wants to avoid unwanted attention.

The pinecone fish is popular in marine aquariums due to its unusual appearance and bioluminescence, but it is better suited to the experienced aquarist. As they are largely active at night, they prefer dimly-lit aquariums with plenty of nooks, crannies in which to hide during the day, and several peaceful tank mates. Its preferred food is live brine or ghost shrimp, although it will adapt to frozen foods with coaxing.