Flounder fish - flat bottom dweller

Description

Many millions of years ago, fish were no different from others and had eyes on both sides of their heads. In order to protect itself from numerous predators and not remain hungry, the Kalkan turned over on its side and merged with the bottom topography. This position allowed the cunning inhabitant of the seas to successfully hunt, burrowing into the depth of the bottom and unnoticed to escape from predators, raising a muddy sand cloud. In the process of evolution, the second eye moved to the top, and the lower side turned into the abdomen.

It’s interesting to watch how smoothly and slowly the kalkan swims; it seems that you won’t find a more phlegmatic creature in the sea, but this is a misconception; in a moment of danger, the Black Sea flounder develops considerable speed. Life expectancy is up to 15-16 years, but some scientists suggest that the kalkan flounder can live up to 30 years. What does the unusual fish look like and what differences does it have?

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Description of flounder, fish lifestyle and habitat

Aquarist with many years of experience

The flounder family includes many species of fish with different habits and habitats, but they also have common features. All of them lead a bottom lifestyle, prefer to live at depth and have a flattened body shape in the form of an oval or diamond. All members of the flounder family are a delicacy that is loved by many people. Knowing where flounder lives, experienced fishermen can easily find and catch it.

All types of flounder are bottom-dwelling, prefer to live at depth and have a flattened body shape.

Representatives of the flounder family live on average 20-30 years and have a rather unusual and interesting appearance, which makes it possible to distinguish it from other varieties of fish. The main distinguishing features are the following:

• the body is flat and plate-like, completely framed by a fin with many rays;
• asymmetrical head, turned to the right or left;
• eyes are closely spaced and function separately from each other;
• the slanted mouth has many sharp teeth;
• on the side of the body where the eyes are located, the scales are of a darker shade, and there is also a wide gill slit;
• the tail is very short and equipped with a fin without notches;
• the side that is devoid of eyes has a lighter shade and dense skin.

To survive in the sea and river, flounder has learned to adapt to any landscape and change body color

At birth, fish fry have the same structure and appearance as all other fish. But gradually irreversible metamorphoses occur, which lead to a shift of the mouth and eyes to the right side of the head.

After transformation, the fish turns over to the blind side , which gradually atrophies and begins to be used by the flounder as a flat belly for the convenience of lying on rocks and the bottom. But in river flounder, the changes occur in the opposite order - the eyes and mouth move to the left side of the head.

To survive in the sea and river, the fish has learned to adapt to any landscape and change body color. Because of this, it is often called the “water chameleon.”

slightly salty and fresh water bodies as their habitat . It is distinguished by a rounded body and numerous spines along its perimeter. The sighted side may be light brown to olive in color with numerous spots. Grows up to 3 kg in weight and 50 cm in length.

In order for its clutch to develop fully, the fish needs to constantly receive a large amount of oxygen from the water column , which is achieved through regular drift of individuals, but this is only possible in salt water, due to its density. In fresh water bodies, the larvae settle to the bottom and die. For this reason, flounder goes to the sea to spawn.

Most often, fish use Baltic waters for these purposes. Therefore, another name for it is Baltic flounder. It is widespread in the coastal zone.

River flounder chooses both slightly saline and fresh water bodies as its habitat.

The habitat of this species of flounder is the northern waters of the Pacific Ocean . The freshwater form is most often located in lagoons, bays and lower reaches of rivers. The star-shaped species is represented by individuals with left-sided eyes. It has a dark color and wide dark stripes on the fins.

It got its name from the star-shaped spiked plates on the sighted side of the body. Most often it is called the Pacific river flounder. Its dimensions in most cases do not exceed 60 cm with a weight of 4 kg. But fishermen tell cases when this species grew up to 90 cm and gained weight of more than 9 kg.

The star-shaped appearance is represented by individuals with left-sided eyes

This fish looks very similar to flounder, but belongs to a different family - Scophthalmidae. Found in the North Atlantic, Black, Baltic and Mediterranean seas. Often individuals of the Kalkan grow up to a meter in length and reach a weight of 20 kg.

A distinctive feature is the left location of the eyes , the rounded shape of the body and a large number of spines located over the entire surface of the sighted side of the body.

But the fish feels great not only in sea water, it is found at the mouth of the Don, Dnieper, and Southern Bug. Here you can also find a smaller variety - the Azov diamond, which does not grow more than 40 cm in length.

This species of river flounder is represented by fairly large individuals with an elongated, dark-colored body and brown fins. Most often it can be found in the Kara, Barents and Bering seas.

Fish spawn in winter. Reproduction occurs under ice at sub-zero water temperatures. During the warm season, she gains weight and tries to stay in the fresh waters of the Yenisei, Ob and Turuga.

Marine species of flounder are characterized by a variety of sizes, shades of the sighted and blind sides, and different body shapes

Salt water is home to many species of flathead fish. They feel great both in shallow water and in deep water. All of them are characterized by very different sizes, shades of the sighted and blind sides, as well as different body shapes.

The most popular is the common sea flounder, which lives in slightly and highly saline waters at a depth of more than 200 meters. This individual is the most desired prey of fishermen. The main color of flounder is dark green with small orange or red splashes . It can reach one meter in length and 7 kg in weight. It perfectly knows how to blend into the bottom and hide from predators.

It is also called sea bottom fish. A distinctive feature is the forked lateral line and sharp fin. The blind side is painted milky, and the sighted side is most often represented by a brownish-brown color.

In nature, there are two varieties:

1. Southern white-bellied flounder, which lives in Primorye and the Sea of ​​Japan.
2. Northern - found in the Okhotsk, North and Bering seas.

This species of flounder lives from the Atlantic to the Arctic Ocean. The largest size was observed in the white halibut living in the Pacific Ocean. It grows up to 450 cm in length and reaches a weight of 350 kg.

A distinctive feature of the halibut is the same color on the sighted and blind sides.

A distinctive feature of this species of flounder is the same color on the sighted and blind sides. The smallest representative of the species is the arrow-toothed halibut, which weighs only 7 kg and does not grow more than 80 cm.

Most fishermen consider halibut a real delicacy. But black fish is especially valued, which differs not only in the color of its scales, but also in the shade of its flesh.

Due to the diversity of species and the ability to quickly acclimatize, flounder is widespread throughout the Eurasian continent and is found in inland seas . Most of them adapt well to fresh or slightly salted water bodies with access to the sea. Knowing where the flounder is found, fishermen go hunting and return with a wonderful catch.

In general, the fish leads a solitary lifestyle, perfectly able to merge with the bottom. Quite a lot of time it remains motionless at the bottom or buried in the ground. This is a kind of camouflage method, which perfectly helps to hunt and protect against predators.

Flounder leads a solitary lifestyle, perfectly able to merge with the bottom

Flounder seems to be a rather clumsy and slow fish. But she is actually a very good swimmer. Over short distances, it is capable of developing quite high speeds.

Swimming near the bottom, it raises a suspension of silt and sand behind it, thereby remaining unnoticed by predatory fish and managing to catch prey.

Depending on where the flounder lives, it can feed at night or during the day. Most often, small animals become food for it. Adults feed on small fish, larvae, crustaceans and caviar, but most of all flounder loves shrimp and capelin.

The eyes are located on one side of the head, so the fish can successfully gnaw shellfish from the soil without suffocating. And its jaws are so strong that it successfully cracks the shells of crabs and mollusks. The high value of flounder is due to the fact that it feeds mainly on protein foods .

External structure

Many people, in photos or live, have seen a fish that looks like an irregular pancake, has a crooked mouth, and both eyes are located on the left side of the body - this is what distinguishes the Black Sea flounder kalkan from its right-sided relatives. The individual belongs to the species – river flounder (Platichthys flesus), class Ray-finned, order Flounder. The color of the “sighted side” is brownish-yellowish with dark brown spots or completely monochromatic, the belly is light, almost white. For protection, they use mimicry, merging with the water column or the seabed.

The peculiarity of the fish is that it has no scales; its place is taken by pointed bony outgrowths. The predator's teeth are sharp and bristle-shaped, located in the form of ribbons on both jaws.

The round body is due to the height of the fish, which is 80% of the length; it is the largest representative of the flounder. The maximum dimensions of the Black Sea Kalkan reach 80-85 cm with a weight of 12-15 kilograms. Females and males become sexually mature at 6-11 and 5-8 years, respectively, and is the most fertile fish in the Black Sea basin.

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River flounder

The species Platichthys flesus, large in population but poor in related taxa, has successfully acclimatized for permanent residence in fresh and slightly salty water. It is distinguished by a rounded body and spines on the lateral line. The sighted side has a dull brown or olive-brown color with chaotic yellow and dark specks. It will grow up to 3 kg with a body length of 50 cm.

For full development, the clutch of flounder must constantly receive a fresh supply of oxygen due to drift in the water column (pelagic eggs). But this is only possible in a dense salty environment (from 10 ppm). In freshwater rivers, the larvae do not maintain buoyancy, sink to the bottom and die, so the fish go to sea to spawn.

To learn more:

Sea wolf, or sea bass: description of fish, catching, breeding

The cool Baltic is ideal for these purposes with a vast basin, low salinity (11-12%), a long coastline, moderate depths of 30-50 m and a rich food supply. The river species is also officially called the Baltic flounder due to its wide distribution in the coastal zone, inflowing rivers and the sea.

Star flounder

The species Platichthys stellatus lives in the northern waters of the Pacific Ocean (Bering, Okhotsk, Chukchi, Sea of ​​Japan). The freshwater form inhabits lagoons, bays and lower reaches of rivers (150-200 km from the mouth). It has left-sided eyes, dark color (greenish, brown), wide black stripes on the fins and star-shaped spiked plates on the eye side. Due to its distribution, the taxon is also known as the Pacific river flounder. The usual size of the fish is 50-60 cm and weighs 3-4 kg. There are frequent cases of catching large individuals weighing 7-9 kg (75-90 cm).

Black Sea Kalkan

The fish is similar to flounder, but belongs to a separate family called Scophthalmidae. Inhabits the North Atlantic and the Black, Baltic, and Mediterranean seas. It grows over a meter in length and weighs up to 20 kg. It is distinguished by the left location of the eyes, its round shape and a large number of tuberous spines scattered over the entire surface of the brown-olive sighted side. In addition to the marine environment, it thrives in the lower reaches of the Dnieper, Southern Bug, and Dniester. Due to the increased salinity of the Sea of ​​Azov due to the shallowing of the inflowing rivers, the Black Sea flounder has spread to the mouth of the Don. A smaller subspecies also lives here - the Azov diamond, which will grow in length to 40-45 cm.

Arctic flounder

A cold-resistant Arctic species (Liopsetta glacialis) with an elongated oval body of a uniform dark brown color and brick-colored fins. Prefers soft silty soil. Inhabits the Kara, Barents, White, Bering and Okhotsk seas. It reproduces in winter under ice, at negative water temperatures (down to -1.5°C). Often the warm feeding season is spent in the low-salt lower reaches of Siberian rivers. Found everywhere in the Kara, Yenisei, Ob, Tugur.

Population conservation

Spawning begins in May and continues until the end of June or July; during spawning, 3-13 million eggs appear, practically without a drop of fat. They float freely in the water closer to the surface. The large amount of caviar is explained by the fact that a huge part of the small balls die from unfavorable conditions and become food for fish and animals that feed on zooplankton. Out of 1 million eggs, only 1000 prelarvae will survive, of which, 4-5 day-old fry with a formed mouth, only 40-50 individuals will grow, the rest will become prey for predators or die of hunger, by the end of summer 10-12 fish out of a million remain.

What kind of individual

Kalkan belongs to a species of ray-finned fish of the order Flounder. In addition to the Black Sea, there is an even smaller subspecies - the Azov. Adults of this fish, which are already 5-7 years old, spawn in the spring at depths of up to 70 meters. In the summer they go to greater depths and return to the shore in the fall.

Mature individuals stand out among other fish by their very high fertility. Some females lay up to 20 million eggs, with an average number of 5-6 million. But not all of them survive; many die from predators.

Flounder fry at first look like ordinary fish with symmetrically located eyes. The eyes begin to shift when the fry is about 15 cm long. The fry acquire the shape characteristic of the Kalkan later, at a length of 25 cm. These fry are popularly called “piglets”. It is at this time that they often become prey to predatory fish and birds. Large fish have practically no enemies. In summer, flounder fry live at shallow depths of up to 10 meters, and closer to autumn they move away from the shore. In summer you can even see them near beach areas.

The Azov Kalkan likes to live at great depths in winter and summer, and during the rest of the year it moves to shallower places. In winter and summer it stays at depth, in spring and autumn it moves to shallow water. Adult fish often lie on the bottom with their blind side. They burrow into the ground. until only the eyes and part of the head remain on the surface. The habits of both the Black Sea and Azov species are the same. Adult fish are typical predators. They hunt mainly at night.

The diet of fish includes, first of all, mollusks and organisms living in the soil. Kalkan feeds on crustaceans and worms. Rarely, but he comes across gerbils for lunch. They say that a particularly large predator can quite successfully hunt in the water column, overtaking anchovy, herring and even fast mackerel.

Habitats

The Black Sea flounder kalkan lives in four seas: the Adriatic and Marmara, the Black and Azov. Slightly smaller than the Crimean Kalkan, the Azov species. It is found on the western coast of Crimea, near Tarkhankut and the shores of Feodosia, in the Kerch Strait, and the Bosphorus. It prefers a muddy bottom or shell bed; it swims to a depth of more than 100 meters only during spawning. In the off-season it rises to the surface, and in summer and winter it stays near the bottom, so vacationers on Crimean beaches often manage to see and take photos of medium-sized kalkan flounder.

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Habitat

Flounder can be seen in the Azov or Black Sea seas, and they are also found in some areas of the Mediterranean Sea. Sometimes fishermen come across Kalkan at the mouths of the Dniester or Dnieper, also on the coasts of the Kerch Strait, Western Crimea. Kalkan is still found in the Gulf of Feodosia and is found in coastal waters in the Nikolaev and Kherson regions.

Habitat

Flounder loves muddy or shell-like soils. Depth - up to 100 meters. A smaller subspecies of this fish is found in the Sea of ​​Azov. Kalkan usually spends summer and winter in the depths and does not rise. And in spring and autumn it floats up, rushing to shallow water. In summer, vacationers can see large young fish swimming near the bottom in sunny beach areas.

Appearance

The flounder has an elongated, wide body, slightly flattened. Height is up to 80%. sometimes more. The body is tuberous, covered with small bony tubercles. From the outside, the flounder resembles a slightly elongated flat pancake with fins and a tail. The eyes of a flounder are on the left, at the top. The fins on that side are asymmetrical. The belly of the flounder is white, and on top, where the eyes are, it is brownish, with small reddish spots scattered along the back. The sea otter has no scales, but upon noticing danger, the fish can instantly change color, adapting to the color of the bottom. The fish's jaws are equipped with bristle-like teeth arranged in the form of dense ribbons.

Nutrition

Flounder is a predator. Its victims are small fish, crustaceans, and some mollusks. An adult Kalkan needs 130-150g of fresh food daily. Most of all he loves small bottom fish and crabs:

• red mullet;
• anchovy;
• sprats;
• horse mackerel;
• Black Sea haddock;
• sprat;
• herring;
• fry.

Reproduction

Male flounder mature for reproduction at 5-8 years, females at 6-11 years. Reproduction in fish of this subspecies occurs in depths of 25-70m, surrounded by open sea. Favorable temperature should be 8-12 degrees. The breeding period occurs in March-April, then continues until June. In some subspecies - until July. However, the peak occurs in May. One fish can produce up to 30 million newborn eggs. The Black Sea flounder is considered the most prolific among the fish of the Black Sea. Such generosity is understandable, because many young animals die from predators, unfavorable conditions, and human activity.

What does it eat?

Small fish such as anchovy, sprat and sultana, as well as crustaceans (crustaceans, crabs) make up the diet of flounder in the Black Sea. The creature is quite voracious; an adult eats 150 grams of food per day. The lifestyle is not very diverse; the flat predator rests buried in sand and muddy soil and looks out for prey with its remaining eyes.

INTERESTING: Kalkan is born like most fish and swims like them. As the flounder grows, it descends and lies on its side on the bottom, gradually the eye moves upward and the swim bladder disappears.

Chem. composition and KBJU per 100 g

It’s not for nothing that Kalkan is caught on a large scale; it has few bones, no scales, is tasty and brings a lot of benefits. Most of all it contains cobalt 20 mcg, phosphorus 400 mg, chromium 55 mcg - this is more than the daily norm, selenium 26.6 and iodine 50 mcg.

Vitamins:

• A – 2.2%
• B1– 7.3
• Choline – 13
• B5 – 3.7
• B6 – 5
• B12 – 37
• C – 2
• D – 28
• E – 4.2
• RR – 8.

Macro and microelements in mg: potassium 320; calcium 20; manganese 35; sodium 200; chlorine 165; iron 0.7; manganese 0.05, zinc 0.45. Contains trace amounts of molybdenum and copper.

Polyunsaturated fatty acids: Omega-3 – 0.46 and Omega-6 – 0.11 grams.

Calorie content in 100 grams of product is 84.5 kcal, fat – 1.3 g, protein – 18.2 and ash – 1.6 grams.

Flounder

Product Description

There are about 500 species of flounder fish in the world. Flounder is found in the Northeast Atlantic, from the White Sea to southern Portugal, in the North Sea and the western Mediterranean Sea. It also penetrates the brackish waters of river mouths and lagoons in search of food. About 30 species of this flat fish live in the seas washing the territory of our country alone.

The flounder's body appears flat and its head is asymmetrical. In fact, what appears to us to be the belly and back are the two sides of the fish. In some species of flounder, the light “bottom” becomes the right side, and in other species, the left side. Flounder can change the color of the upper side of the body depending on the color and pattern on the bottom. She reproduces it so similar that she becomes almost invisible.

Interestingly, newborn flounder is no different from other fish. Her body is symmetrical, and the eyes are located on both sides of the head, but as she grows older, one eye begins to move from the lower (“blind”) side to the edge of the head, this occurs due to uneven growth of the body. Subsequently, both eyes appear on the upper (“eye”) side. True, there are several exotic species: their moving eye stops exactly on the edge of the head.

Flounder meat is rich in phosphorus salts, but there is practically no fat. Flounder is a source of vitamin B12 and omega-3 fatty acids. Fish contains vitamins such as A, D, B12, E, thiamine, riboflavin, nicotinic and pantothenic acid, pyridoxine. Flounder contains useful amino acids such as aspartic, threonine, serine, glutamic acid, glycine and many others, which help reduce blood cholesterol levels. Flounder contains many minerals and trace elements - sodium, potassium, calcium, iron, selenium, zinc, magnesium, phosphorus, copper. Fish also contains large amounts of iodine.

Types and varieties

Flounder is the name given to two species of commercial fish of the flounder family, belonging to the genera Bothidae and Pleuronectidae and distributed in the coastal waters of several seas.

The European species of flounder and Japanese olive flounder are of greatest interest for fishing on an industrial scale. Species native to the western and northern Atlantic are popular among sport fishermen. Only medium and large-sized species of flounder are of gastronomic interest. The European species of flounder is about 1 m. There are also species, for example Oligolepis Tarphops, which grow only up to 4.5 cm and reach a maximum weight of 2 g.

The Black Sea variety of flounder is called kalkan - it is a fairly large fish, it grows up to a meter in length, sometimes weighing up to 10 kilograms. Kalkan meat is white, tasty and not very fatty.

Off the western coast of Kamchatka, a significant part of the flounder catches is the so-called yellow-bellied , or four-tubed flounder - one of the most delicious and valuable Far Eastern flounder.

How to cook

Most flounders have very tasty and tender meat, so many representatives of this order are commercial fish in many countries. This fish can be prepared in a variety of ways. Usually the whole flounder or only its tender fillet is fried in a frying pan.

In Normandy, flounder is baked with cider or with mussel and champignon sauce. In Greece they cook it with tomatoes. The Danes often use mushrooms together with flounder. And in Germany, boiled flounder with various sauces is most popular. When cooking flounder, white wine is often added to the broth.

Why is it useful?

Eating Black Sea flounder meat 2-3 times a week will improve visual acuity, strengthen bones and even promote rapid healing of wounds. The product is suitable for diets of those wishing to lose weight, allergy sufferers and people with reduced immunity:

• 20% of easily digestible protein contained in fish has lipotropic properties, which is important for people who want to lose extra pounds;
• for a person suffering from allergies, this product is very useful, the Black Sea Kalkan cannot be raised in captivity, which means the meat does not contain antibiotics or growth hormones that provoke attacks or rashes;
• omega fats, which are present in fish meat, will help children, the elderly and adults who have suffered serious illnesses, recover faster, and improve their health;
• choline reduces the likelihood of suffering from Alzheimer's disease in old age, improves memory and brain function in students and mental workers;
• even a small amount of iodine entering the body with Kalkan meat will restore vigor, restore the menstrual cycle and relieve swelling. For thyroid diseases, be sure to include it in your daily diet.

In addition to the listed properties, flounder meat is an aphrodisiac for women and men, has a beneficial effect on the heart muscle, and prevents cancer.

Selection rules

To prevent valuable substances from evaporating from the Kalkan, you need to know how to choose this fish. Fresh or frozen carcass should not have a dull color. Bright and distinct spots and shine indicate that it is of good quality and suitable for consumption. Pink gills, non-cloudy eyes and quick recovery after pressure - everything is the same as when choosing any other fish.

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ATTENTION: You should not pay attention to the white side of the Kalkan, it does not change shade.

How to clean

The absence of scales allows you to fry, steam or boil Kalkan with skin, but for those who are squeamish - a small master class. Pour boiling water over the frozen carcass (fresh is not necessary), cut off the fins on both sides and the tail with a sharp knife, making two cuts in the shape of a triangle and cut off the head. These operations can be done with kitchen scissors. Then lift the skin from the side of the tail and remove it, it is better to do it with gloves so that it does not slip in your hands. Clean out the insides and the flounder is ready for cooking.