Flashlight Fish- A Species That Can Produce Light While Schooling

Fishing is a fascinating hobby to get close to nature. Most of us have this hobby of fishing, and it is like an escape from everyday bustle. Those who have a liking for fishing know many kinds of fish and their natures. It is essential to know different types of fish if you are interested in fishing.

The underwater world is very much compelling, and scientists have been researching the underwater species for so long. The scientists want to discover more of the new species and new interesting characteristics of them. They have successfully found new aquatic species and their fascinating behaviors.

Flashlight fishes are this kind of interesting underwater species. Flashlight fishes can produce light while they are schooling. This natural characteristic of this kind of fish has made the scientists enthusiastic about studying more on them.

Discovery of the Flashlight Fishes:

In 1967, American and Israeli workers first found these fishes’ interesting characteristics at the Gulf and Eilat shores. They noticed that the flashlight fishes remain in the dark caves and reefs underwater in the daytime. They venture out of the dark caves or reefs at night or moonlit night and start roaming around. While they are schooling together, they lit flashlights to mark one another’s position.

Where Flashlight Fishes Live and What They Eat:

Flashlight fishes are mostly found throughout the Pacific Ocean and in the eastern Indian Ocean. There are three types of a flashlight or lantern-eye fish, and each is in a separate genus. Two of them live in tropical marine habitats of the Indo-Pacific region, and the third type lives in the Caribbean. They live in dark places underwater like caves or between giant coral reefs maximum time of the day.


FlashLight Fish in side

Their eating habit is not different from other fishes. Flashlight fishes mostly eat zooplanktons or animal planktons like most other fishes to live. They might also consume small fishes that resemble those tiny planktons.

Mysterious Eyes Glow in the Darkness:

Though the character of flashing light of the lantern-eye fishes was discovered a long time ago, the researcher found the mystery of this nature in 2016. They used a very sophisticated camera to observe the fishes’ movement and the actual source of their light. After observing this charming phenomenon, they found out the source of this light and its usefulness.

The mysterious reason for these unique characteristics of flashlight fishes is bioluminescence. They have luminescent below their eyes. Bioluminescent bacteria live there relying on the symbiotic relationship with the hosts, in other words, the fishes. The bioluminescent produces a chemical reaction on its body, and the chemical energy releases in the form of light.

They produce these chemical reactions by taking the nutrients from the host’s body. In return, these bacteria help the fishes in many ways to live and to survive. The fishes have created special organs to house these bacteria called photophores. Thus the bioluminescent bacteria and flashlight fishes help each other by building a close symbiotic relationship for the sake of each other’s survival.

Beautiful and Useful Eyes Glow of Flashlight Fishes:

Beautiful and Useful Eyes Glow of Flashlight Fishes

Image Credit: www.amnh.org

The bioluminescent bacteria produce a neon blueish glow below the eyes of the flashlight fishes. It looks really wonderful when they roam around forming a school at night and create a blinking effect with the flashlights below their eyes. Besides, the bioluminescence helps the lantern-eye fishes in so many ways to live under the water.

  • Grabs the attraction of the prey and helps to capture them.
  • Creates predator deterrence and confusion.
  • Attracts the attention of mates.
  • Coordinates their schooling together.
  • Helps communicate between the members of the same species.
  • Supports navigation and signaling while schooling.
  • Serves the fishes with extra oxygen through a system of blood vessels.

Blink and Run:

The flashlight fishes can even rotate the photophores downward and cover the light. They use this defense mechanism to evade predators and to make them confused about their movement, and the behavior is called “blink and run.” So bioluminescent is absolutely useful for self-defense.


Schooling provides them with many facilities. It becomes tough for the predators to prey on them for their zigzag schooling with a frequent blinking light. It is almost impossible to know more about them and their characteristics for their tiny size and elusive nature.

It is still unclear how the fishes coordinate their glowing up while schooling, and there needs a lot more research. Some studies show that only a few individuals glow up while schooling and help others. But it is still unknown who decides to glow and when.

Less Blink and Prey:

Flashlight fishes use their light blinking to prey and collect food. It is an interesting way of preying. The researchers found out that the fishes blink very frequently, 90 blinks per minute, and the light remains on or off for an equal amount of time.

When they can detect any zooplanktons or animal planktons, the number of their blinking decreases to detect and illuminate them with their bioluminescent light, which means they keep the light on longer than in the absence of any prey. They frequently blink five times less in that situation. But the natural condition is a matter of fact in their blinking habit.

Thus bioluminescent bacteria help the flashlight fishes have their food and survive. The symbiotic relationship between them has made sure of this mutual survival.

Flashlight Fish Use Bioluminescence to School at Night

More to Know About Flashlight Fish:

People know more about the land animals or insects who use bioluminescence to communicate as they are easy to research on. For instance, we know much about fireflies. We know a lot about their movement, the pattern of their blinking, and so on.

Scientists and researchers have discovered only a little information about the deep sea flashlight fishes. There is left a lot to know about them. But it is challenging to know about the deep-sea species for difficulties of reaching there. They are trying their best to learn more about their characteristics and nature.

The recent analysis and research suggest that the number of bioluminescent flashlight fishes is increasing. There can also be many types of them, about whom we are not aware. Studies show that bioluminescence has evolved 27 times in 14 major fish clades.

It is likely possible that one day there will be robots to study deep-sea species and marine lives. Then it will be so much easier to observe and record every movement they are taking under which natural condition. We will know every tiny detail about them, and we earnestly hope that day is not so far. The deep-sea world will not be mysterious anymore to us if we become successful to reach the goal.

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