Beneath the surface of oceans, rivers and lakes lies a captivating world made up not only of colourful corals and diverse marine animals, but also of fascinating fish that amaze us with their size, beauty and unique features. Let us dive into this underwater realm and discover together the largest and most interesting fish that beautify and bring life to the waters of our planet.
The underwater world is full of fascinating creatures, and fish play a unique role among them. It is not just about size, but also about colours, shapes and behaviour.
Table of contents
Ocean sunfish (Mola mola)
In the endless depths of the oceans swims one of the most interesting and largest fish, one that fascinates scientists and marine life enthusiasts alike. Its shape and giant size make it a truly unique creature. It is called Mola mola.
Mola mola is one of the heaviest bony fish in the world. Its flat shape and enormous weight, which can reach up to 2.3 tonnes, give this fish an air of mystery.
One of the fascinating abilities of Mola mola is the way it swims. Its broad body and fin movements give it an unmistakable appearance, and it moves underwater with remarkable ease and elegance. The fish is propelled forward by the sideways beating of its dorsal and anal fins, which move in sync from side to side, a motion compared to the flapping of a bird’s wings. It is the only known animal that uses its originally unpaired fins for movement in this synchronised way. At sea, they usually move at around 0.4–0.7 m/s. This fish is also known for often swimming close to the surface and exposing its upper side to the sun.
However, what makes Mola mola so unique is not only its impressive size, but also its unusual feeding habits. The sunfish is mainly herbivorous, although it also feeds on jellyfish, crustaceans and small fish. Its diet not only provides it with the nutrients it needs, but also has an ecological impact, as it keeps jellyfish populations in balance, which could otherwise cause a disaster in the marine ecosystem.
Arapaima (Arapaima gigas)
In the mysterious waters of the Amazon River swims one of the largest freshwater fish in the world: Arapaima gigas.
The arapaima is a fish that reaches lengths of over 3 metres and can weigh more than 220 kilograms. Its robust body and scales make an unmistakable impression as it moves through the aquatic vegetation of the rainforest. However, what makes Arapaima gigas truly unique is its ability to breathe air. It has special respiratory organs that allow it to take in oxygen from the atmosphere. This adaptation is crucial during the dry season, when many parts of the Amazon River dry up, and fish with this ability survive in the shallows. As a defence, this fish has developed very large, strong and also sharp scales.
Another fascinating feature of Arapaima gigas is its feeding strategy. It is mainly carnivorous and hunts aquatic invertebrates and smaller fish. Its hunting skills are remarkable, especially when it makes a quick and precise attack on its prey. Despite its size and predatory nature, this fish is usually peaceful towards people, which makes it a subject of interest not only for scientists, but also for anglers and freshwater fish enthusiasts.
Unfortunately, Arapaima gigas currently faces threats from overfishing and the loss of its natural habitat caused by deforestation in the Amazon.
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Giant oarfish
The giant oarfish is a marine fish that lives in the depths of the oceans. One of its most striking features is an extremely long dorsal ray, which can be several times longer than the fish’s body itself. This dorsal ray is often red or pink, which earned it its Czech name meaning “red-maned”.
The fish has a flat, silvery body and a small head. Its overall appearance resembles a snake. The oarfish reaches lengths of up to 8 metres and is the longest bony fish.
Giant oarfish are usually found at great depths, where they move alone or in small groups. They are plankton feeders that eat tiny marine organisms such as crustaceans and small fish. Much is still unknown about their behaviour and life in the wild, because they live in deep ocean areas that are difficult for scientists to reach.
Piranha
In the mysterious waters of the Amazon River and the surrounding water systems swims a predator whose name inspires both respect and fear: the piranha. The piranha has earned its reputation not only thanks to its distinctive appearance, but above all thanks to its remarkable hunting instinct.
One of the most interesting aspects of piranha behaviour is their hunting strategy. They are mainly carnivorous and hunt larger prey in shoals. The moment prey appears, piranhas attack at lightning speed. Their sharp teeth and strong jaws can easily bite off flesh. Piranhas cannot chew their food, so they swallow the torn-off chunks whole. Within a few minutes they can strip all the flesh from their victim, leaving nothing but bare bones. Piranhas remain aggressive not only when hunting, but also when defending their territory.
However, the image of the piranha as a dangerous predator does not always match reality. Most piranhas feed on small fish, crustaceans, insects and birds. Attacks on people are rather rare. Despite their reputation, piranhas are a key part of the Amazon ecosystem, where they help maintain the balance between different species and control the population of small fish.
Parrotfish
Parrotfish belong to the family Scaridae and are found in tropical and subtropical waters all over the world, especially in coral reef areas. This diverse group of fish includes several dozen species, each with unique colours, shapes and behaviour.
One of the characteristic features of parrotfish is their ability to chew and at the same time clean the coral reef. They have strong jaws and beak-like teeth that help them eat coral rock, from which nutrients and algae are then extracted. As a result, parrotfish can produce fine white sand, which is sometimes visible on the seabed around coral reefs.
The colours of parrotfish are very striking and varied. Many species have beautiful shades of blue, green, orange and purple. These colours not only serve as a defence mechanism against predators, but also help identify species and reproductive states during the mating season.
Anglerfish
Anglerfish are fish with a distinctive appearance that can seem like a combination of several sea creatures. The body is relatively low and wide, which helps them blend in better with their surroundings. Some species may also have spines or “hooks” on their heads. The fish are known for their long tail sections. They lure their prey towards their mouths using a light source.
The colouring of anglerfish depends on the environment in which the fish lives. The usual colouring is brown, red or greenish grey with irregularly placed spots.
Anglerfish live in deep oceans all over the world. They can move along the seabed and hunt small marine animals, such as little fish and crustaceans.
All in all, anglerfish are an interesting and unique group of fish that give us a glimpse into the secrets of the deep oceans, where they adapt to extreme conditions and live in relative isolation from the surface.
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