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There is a variety of fish in the world, but there are a few fish in the deep sea that is rarely seen. There is not one deep ocean fish, but there are many more that have never been explored. 

Deep ocean fish

Can you believe that more than 80 percent of the ocean has never been mapped, explored, or even seen by humans, although a great percentage of the moon and other planet surfaces has been mapped and studied? 

There is much more to learn, but there have been made a few amazing discoveries about deep ocean fish. 

Why the deep ocean fish looks weird? 

You can notice that most of the deep ocean fish look ugly and scary. They look so because they have adapted to survive in harsh environments. The deep ocean is entirely different from shallower water. 

By most standards, the deep ocean begins below 1,000 m (3,280 ft). In the zones of the ocean, the deep ocean is in the bathypelagic zone and extends down to the abyssopelagic zone (4,000–6,000 m / 13,123-19,685 ft deep) and beyond. 

Dissolved oxygen levels are also low, and the water temperature can range between a very cold -1.8 and 3 °C (28.76-37.4 °F).

These layers are in complete darkness with extreme depth, and anything living there exists under incredibly high pressure.

It is easy to survive in shallow water and that is why they look prettier. The deep sea fish evolves for practical purposes. The low temperature, incredible water pressure, lack of light, and lack of food, make the fish that lives there to look ugly. 

They have evolved the characteristics that are needed to survive in these extreme conditions, and these can make them look weird or ugly by human standards. To survive in such conditions successfully, it is required for the fish to adapt to it resulting in ugly and scary looks. 

Deep sea fish

Deep-Ocean Hatchetfishes

Deep-Ocean Hatchetfishes

These odd-looking creatures are amazing as well as scary to look at. The hatchet fish gets its name from their odd body with a thin rear section making them resemble a hatchet ax. 

It is born with pelvic bones tilted downwards and large eyes that point upward. It has a blade-like body that cuts through the water column with barely a trace. 

Hatchetfish are well camouflaged. Along the bellies of these deep-sea fishes, there are light-producing organs in rows, shining in a pale blue light matching the daylight filtering down from above.  

They have adapted to the incredibly low light conditions found at the depths of the sea.  As a result, their eyes become extremely sensitive to light and makes out the slightest shadows amongst the very dim light of the surface.

There are around 40 species that can be found in oceans all around the world. Marine hatchet fish can be found in depths of 500 to  4000 ft depending on the size and the anatomy of the species. 

Most of them are very small in size growing only to a few centimeters in length. 

They use bioluminescence to attract potential mates and after mating,  the female lays a huge number of tiny eggs that will float in the water.

They have an incredible ability to remain invisible to the eyes have predators. They do this by emitting light from their bodies. During the daytime, they hide in the depths of the ocean and come to the surface at night. 

They eat plankton, tiny crustaceans, and small fish,  while also using the ability to jump and fly to catch and eat insects.


Blobfish is the world’s ugliest fish that lives in some of the deepest zones of the ocean at depths between 600 and 1,200 m where there is an incredible pressure that can be more than 100 times.  

Its body is squishy, with soft bones and very little muscle. When you catch a blobfish in nets and bring it to the surface, the decompression expands and causes its skin to relax. The features get distorted and the characteristics give it a big nose. 

When it comes to the land or the deck of a boat, its gelatinous tissue doesn’t hold its structure, so it collapses into a shapeless mass much like a washed-up jellyfish.

They have adopted a way of living that allows them to survive as a blob in the deep ocean.  They tend to float along just off the bottom of the sea and they eat whatever floats right in front of them and that fits into their mouths. 

The few hard bones and gelatinous mass has an advantage in crushing depths where it lives where it can keep itself from being crushed due to water pressure.  At the bottom of the sea, it looks very different appearing much more compressed looks like a fish with quite odd looks. 

The body composition gives the fish the right buoyancy the float along across the bottom of the sea.


This fish is a deep ocean fish that has long and menacing fangs. The adult fish is small that reaches only about 6 inches in length.  It gets his name because of the teeth that are the largest in the ocean in proportion to body size.  It’s so long that the fangtooth has an adaptation for it to close its mouth.

It has special pouches on the roof of its mouth that prevents the teeth from piercing the fish’s brain when its mouth is closed. 

It can be found deep in the ocean would be 5,000 meters (16,404 feet),  making it one of the deepest living fish.  You can also find them commonly between 500 and 2000 meters.  It stays in deeper areas of the ocean during the day and will migrate up to Shallower water to feed at night.


They are more active than many other deep sea fishes and rather than sitting and waiting for food,  they seek out food.  They have huge mouths and long teeth to attack prey. 

Although they look menacing and seem to be voracious predators they are actually harmless to humans. 

They are dark colored and can either be solid Brown or black in color. But they do not have light-producing organs for communication or to attract prey.  Instead, they heavily rely on the sense of smell and get benefits from even the slightest bit of sunlight. 

Living in an extreme environment make it difficult for scientist to study their behavior. Therefore little is known about mating preferences.  But they are known to reproduce via external fertilization where the females release the eggs and males release their sperm into the open water at the same time.


Hagfish are also known as slime eels. They have five hearts, no jaws, eyes, and no stomachs. They have poor vision along with a very good sense of smell and touch. They are blind, but they do have eye spots. 

Hagfish live in burrows on the seafloor and locate their food by smelling and feeling as they swim. They prey on small invertebrates that live in the mud. They are noted for their unusual way of feeding. 

They slither into dead or dying fishes and eat them from the inside out and they use their rasping tongue to carry food into their funnel-shaped mouths. Hagfish are notorious for their defensive slime. They secrete sugar and protein mixed into the seawater. 

When expelled, it mixes with the saltwater and becomes a slippery slime. Protein strands within the slime make it extremely sticky. Their eating habits seem to be disgusting but hagfish help clean and recycle dead animals from the seafloor. They also serve as a food source for fish, seabirds, and seals, at least those that can make it through the slime.

No one is sure whether hagfish belong to their own group of animals as they fill the gap between invertebrates and vertebrates, or if they are more closely related to vertebrates.

Glass squid

The glass squids belong to the family Cranchiidae, also known as cranch squids. This deep ocean fish looks strange and flashy. They have bulging eyes, swollen bodies, and short arms, with some other features. 

They are mostly found in the pacific south approximately 900 meters under the sea, even at depths of 1600 meters when they reach their mature age. Like the firefly squids, most glass squids have lighting organs on the underside of their eyes and this allows them to have light in them, and to be seen and differentiated in the dark.

They actually look really attractive and different from other squids. It is a blue creature but looks transparent, which means it may seem a bit bluish. Its size is approximately about 180 millimeters and has a thickness in its mantle of a few centimeters. 

glass squid the deep ocean fish

The female glass squid is a little larger than the male. They have ten tentacles, where eight of them are small and two are at the end of their bodies. Their stomachal gland is the only part of their bodies that can be seen clearly. 

The best way for them to defend themselves is by swallowing a lot of water. As a result, they become much larger than usual, which makes them much more threatening. If a glass squid looks bigger than its size, it is because it is the way of defending itself against its possible threats.

The females lay their eggs in numerous large groups, in the plants or rocks, located at the bottom of the sea. The squids get deposited and grow very fast, and mature reaching roughly 190 millimeters in length. The females can have up to 700 eggs, and the most incredible thing of all is that they can be seen through their bodies since they are totally visible.

Football fish

This species is about the size of a football and covered in spines. It also has branches that extend from its head and end in tiny glowing lights. These lights attract prey which is then grabbed by the footballfish’s mouth crammed with sharp teeth.

These are shy and elusive fish and there are around 22 recognized species. The football fish has a large, round, or oval-shaped body resembling a football. They also have very sharp teeth and black or brown scales.

Like many types of anglerfish, there is a strong difference between females and males. The females measure up to 2 feet long and possess the large glowing angler rod that emerges from the head. They also have a covering of round, bony plates on their body. On the other hand, the males measure less than 2 inches long and lack many of the same physical features as the female.

The football fish is primarily found in the deep tropical waters of the Atlantic, Indian, and Pacific Oceans. Because of their deep-sea activity, it’s very difficult to make a proper estimate of population numbers. 

Football fish discovered

These fish have few threats in their natural habitat, but climate change could pose some problems in the future as the temperature of the oceans change. 

They have one of the most unique mating strategies of any animal in the world. the male football fish will actually lose its digestive system as it grows. It is required for them to find a mate quickly or die. 

As a source of attraction, the female’s lure is thought to act in the dark. When it has found a suitable mate, it will bite into her flesh and fuse with her body. 

The male will then lose most of its body parts except for the testes to exchange sperm with the female. In return, the male will receive sustenance through the fusion of their blood vessels. It’s thought that the female can carry multiple around in this manner throughout her lifetime.

Final thoughts

The extraordinary and sometimes frightening-looking appearances of the deep ocean fish are due to the incredibly harsh environment that they live in. It is the combination of complete darkness, extreme cold, colossal pressure, and scarce food. 

Therefore, these fish have developed to look completely different from their shallow-water cousins. They battle to survive in some of the harshest conditions on earth and they are seen to be strange, ugly, or scary as it is a vital evolved property that allows these incredible fish to survive.

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