Two Types of Hatchet Fishes: Freshwater & Deep Sea Hatchetfish
are mainly two kinds of Hatchetfish: The freshwater hatchetfish and deep sea or
marine hatchetfishes. They are named for their hatchet-like shape. Although belong
to the same species, they are quite different in size, body features, and diet.
Hatchet Fish Pictures
Deep Sea or Marine Hatchetfish: Habitat
Marine or deep sea Hatchetfish are a little bigger and “uglier” than freshwater ones. Deepwater Hatchetfish are found about 600-4500 feet below sea level. Their scientific name is Argyopelecus gigas, and they are only about 4 inches long. Their bodies are extremely thin, so swimming is easy and they easily escape predators. They also escape predators easily by matching their light intensity with the light penetrating the water’s surface. This is called counter-illumination. In the deep, insects are unavailable, so they mainly feed on plankton and small fish at night. Their eyes are large, round, and they have very good vision. They are good at catching very faint light and focusing on objects in the water near and far. Its large surface area allows the Hatchetfish to see in many directions and line out silhouettes of fish from above. Their teeth are small and sharp, but they are not used for feeding. Larger Hatchetfish are green or blue in color. Deep sea Hatchetfish are plentiful in Pacific, Atlantic, and Indian oceans. In general, Marine Hatchetfish look a lot like freshwater Hatchetfish, but they have a smaller belly and are thinner.
Deep Sea Hatchetfish Reproduction
It is unknown how, when, and where reproduction takes place. Scientists believe that there is some kind of courtship however. Many eggs are laid after fertilization and hatch in a very short time. Marine Hatchetfish only live for about ten months and die. The population is unstable at the moment, even though they are not disturbed much by human purposes. Fisheries catch them rarely, probably because they will not fall for bait. Their bodies are fragile and the scales are easily abraded.
Freshwater Hatchetfish: Facts
Freshwater hatchetfish are also known as Silver Hatchetfish or the Common Hatchetfish, (although they are actually two of the genera) and are usually silver colored, with a thin body. They are found in South America. The chest of the fish is extended forward, making them look unusual. These fish grow to about 2-3 inches long. They are actually great swimmers, and are kept as aquarium pets. Their tails are simple and Y-shaped. Two horizontal fins are attached above the gills.
Common Hatchet fishes are carnivorous, and eat flies (fruit flies are the best), mosquitoes and their larvae. Occasionally, small crustaceans are available and eaten. In the wild, Hatchetfishes live in slow streams with heavy vegetation. A pattern around the mouth seems to attract bugs. Any prey that falls into the water is quickly swallowed. They do not eat much. They also have quite short life spans and do not reproduce quickly. In fact, it is said that they glow with “blue light” when they die. Hatchetfish do best when they are with other Hatchetfishes.
A special kind freshwater hatchet fish is called Marbled Hatchetfish with the scientific name Carnegiella strigata. They are omnivores prefer various diet including live or frozen food, and vegetables. They eat only foods floating on the water surface.
The odd shape of the hatchetfish is due to a large muscle attached to the pectoral fins, which is used to give the fish an immense and sudden burst of speed, allowing them to leap several meters above the water. While this is rarely used in safe aquarium, it is more frequently used as an escape response in the wild to evade or confuse predators. They may leap from the tank if startled for any reason. When the fish are off the water, they ‘beat’ the pectoral fins to gain additional height in the air, making them a true flying fish than a jumper or glider. Usually, these flights are no more than short trips above the surface, but they can be a few meters high.
Freshwater Hatchetfish: How to Breed
order to take care of freshwater Hatchetfish, their environment should have lots of
foliage in it. Buy water plants, and you can gather them from a lake nearby,
but make sure you find floating plants as they need room to swim. Driftwood is
ideal. Hatchetfishes live best with a group of six or more, or minimum school of three, so a tank should be about
two feet. The temperature should be around 77 degrees, but anything from 75-82
is fine. They don’t like too much light, so keep them out of direct sunlight.
In the wild, Hatchetfish are excellent jumpers, so keep a tight lid on top of
your aquarium in case they are tempted to leap out and suffocate. Filtration is
needed, and your Hatchetfish will enjoy the feel of a stream.
Hatchetfish do not need to be fed anything special. Live food is best, and you can even catch them yourself. Live fruit flies, mosquitoes, and their larvae are excellent for a balanced diet. However, dry food is also taken. If those are unavailable, feed your Hatchetfish occasionally with standard flake fish food, but live food is better.
Don’t worry too much about breeding. Hatchetfish will breed with others once in a while, but the tank won’t usually over populate. Hatchetfish lay their eggs on floating plants and hatch very quickly in about thirty hours. Females are generally bigger and rounded. Eggs can sometimes be seen from the outside, but there is no more identification of whether a Hatchetfish is female or male. Baby Hatchetfish need to be fed just as often as adults with very small food. Ideal foods are crushed flakes, small brine, and infusoria. Infusoria can even be grown using some algae wafers, tap water, and some water conditioner.
Hatchetfish live well with other small fish and are non-aggressive towards other species. They are very active fish and like to play around. A great addition to a medium-sized tank.
Freshwater Hatchet Fish: Genera and Species
|Genus||Common Name||Scientific Name|
Carnegiella (Eigenmann, 1909)
Gasteropelecus (Scopoli, 1777)
Thoracocharax (Fowler, 1907)
Silver Hatchetfish Male and Pregnant Female
Marbled Hatchet Fish
Thoracocharax stellatus Hatchet Fish
Sabrina Yuquan Chen (陈玉泉) (author) from Boston, MA, USA on February 14, 2011:
Thank you, vividimage, for the visit. Indeed, deep sea living things are mostly weird and/or ugly, I wonder how the depth plus saltwater facts play the role to make those strange creatures. Amazing!
B C McCord from Mesa, Arizona on February 13, 2011:
Wow, I enjoyed reading this. Marine life has been of interest to me (periodically) over the years so this was cool to me to read, watch, and view! Thanks!
ps - boy are they ugly critters!