Common catfish is the most massive representative of the catfish family. The second name of the fish is European catfish, this species (Silurus glanis) is described as a freshwater species of fish, large in size and with no scales.
The genus Soma includes 14 main species of the catfish family, these are:
- Silurus glanis – Common catfish;
- Silurus soldatovi — Soldatova catfish;
- Silurus asotus – Amur catfish;
- Silurus biwaensis ;
- Silurus duanensis;
- Silurus grahamii;
- Silurus lithophilus;
- Catfish on the chin;
- Aristotle’s catfish;
- Southern catfish;
- Silurus microdorsalis;
- Silurus biwaensis;
- Silurus lanzhouensis;
- Silurian triostegus.
The most common species among relatives was the common catfish, this is the most striking representative of the genus – Soma.
Characteristic species features
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In the world classifier, ichthyologists classified the genus of catfish as a class of ray-finned fish. According to scientific research, the first representatives of the class, the ray-finned ones, lived in water bodies 390 million years BC. catfish. This is an ancient detachment, as evidenced by numerous atavisms on the body of the fish.
If even in the last century it was possible to catch a river catfish weighing more than 350 kg with a body length of more than 4 m without problems, then today these trophies are no more than 30 kg, and average specimens rarely weigh more than 15 kg. The largest specimen of the caught catfish in our country was recorded by the fish inspection of the Kursk region. It was a trophy catfish weighing 200 kg, it was caught on a section of the Seim River in 2009.
A massive and compressed head in a horizontal plane with a wide mouth and spaced small eyes (relative to the size of the body), these are typical signs of a fish. The oral cavity, dotted with small, brush-shaped teeth, is capable of swallowing prey of almost any size, often birds and small animals that come to a watering hole to a reservoir become prey.
Three pairs of whiskers are placed on the head of the fish, the first pair and the longest are located on the upper jaw, and the remaining two are on the lower. It was thanks to the mustache that the catfish got the nickname “devil’s horse”, there was a belief that the merman, riding on fish in the depths of the reservoir, was kept on top of it, holding on to a pair of mustaches. Whiskers for the “charioteer of the water” serve as an additional organ of touch.
The color of the body of the fish largely depends on the season, habitat, and to a greater extent on the color of the bottom and objects located on it. In most cases, the color is dark and gray, closer to black. In reservoirs with a shallow channel and abundant vegetation, the color of the fish is closer to olive or green-gray, with spots of dark tones scattered over it. In locations where the sandy bottom prevails, the catfish has a color with a predominant yellowness and a light belly.
The fins of the fish have darker tones than the body itself, the upper (dorsal) fin is not large in size, it is almost invisible on a flat body, so it is very difficult to find a catfish lying in a hole at the bottom. The anal fin, in contrast to the dorsal, is larger, flattened and reaches a length of 2/3 of the entire body, located between the rounded caudal and pelvic fins.
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The massive body of the fish is round in shape, as it moves away from the head to the caudal fin, it is more runny, compressed in the vertical plane. The caudal part of the body, like the anal fin itself, is elongated, powerful, but due to the increased weight of the individual, it is not capable of making a speedy fish out of a clumsy firing.
A characteristic and distinctive feature of the European catfish is the absence of scales, this function is performed by the glands, which in turn cover the body with protective mucus.
Habitat
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Common catfish received a habitat in the European part of our Motherland, where it became an object of artificial breeding, in the basins of the seas:
- Black;
- Caspian;
- Azov;
- Baltic.
Due to the heat-loving nature of the fish, in the waters of the Baltic, its capture is rather an exception, and it is difficult to call the caught specimens trophy.
Silurus glanis can often be found in many European rivers:
- Dnieper;
- Kuban;
- Volga;
- Wisla;
- Danube;
- Hay;
- Ebro;
- Diet;
- Rhine;
- Loire.
In the Pyrenees and the Apennines, this species has never been native, it was successfully introduced in the century before last into the basins of the Po and Ebro rivers, where it subsequently increased its numbers. The same situation has developed in the river basins:
- Denmark;
- France;
- The Netherlands;
- Belgium.
Now this species can be found throughout Europe. In addition to Europe and the European part of Russia, Silurus glanis can be found in the northern part of Iran and Central Asia Minor. In the last century, quite a lot of effort and time was spent by ichthyologists of the “Institute of Fisheries” to increase the population of Silurus glanis in Lake Balkhash, where it successfully increased its numbers, as well as in reservoirs and rivers included in the network of its basin. The wild population of Silurus glanis, although it increased its habitat, did not become an object of commercial fishing due to a small population.
Full-flowing rivers, sometimes desalinated areas of the sea near the mouth of the river, have become a favorite place where the catfish feels comfortable.
Most of the subspecies of the Soma genus, in addition to Europe, received favorable conditions for increasing the population in the warm waters of the river basins:
- China;
- Korea;
- Japan
- India;
- America;
- Indonesia;
- Africa.
If we consider the favorite habitats of catfish within the reservoir, then this will be the deepest area with a deep hole. With a drop in water temperature, he will give preference to a pit among the flooded and washed roots of trees, from which his “owner”, even for the time of hunting, sails reluctantly and for a short time.
The period of stay in a chosen place for a catfish can last throughout its life, only extreme circumstances in the form of a scarce food supply, deterioration in water quality can force it to leave its home. The question immediately arises, how long is this species actually able to live? Silurus glanis, according to ichthyologists, can live a life of 30-60 years, but there are confirmed facts that individuals 70-80 years old have been caught.
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Diet
In order to gain such body weight, it is clear that the fish need to eat hard. The diet of Silurus glanis is really like that of a river gourmet, it includes:
- a fish;
- frogs;
- shellfish;
- insects;
- bird;
- small
- insect larvae;
- worms;
- bottom and coastal vegetation.
At the initial stage of growth, the diet of a growing individual includes fish fry, larvae and small crustaceans. With the advent of an adult state and weight gain, the catfish is less likely to conduct a targeted hunt for “food”, it imposingly drifts in the water column with an open mouth, filtering it, dragging streams of water with small prey into its mouth.
In the daytime, the mustachioed predator prefers to lie down in its hole, and when the night coolness comes, it goes hunting. It is the mustache that helps him keep track of the situation and the approaching small fish, which, in turn, are attracted by the swaying mustache, similar to a worm. The hunting tactics are more passive and calculated on luck, only at an early age the catfish pursues prey in the form of small fish, and even then, not for long.
Spawning
Since the formation of a stable positive water temperature of at least 160 From the spawning period of Silurus glanis begins, it coincides with the period of May flowering and lasts until mid-summer, it all depends on the region in which the reservoir is located. Anticipating the beginning of the spawning period, the catfish begins preparations in the form of arranging a nest on a sandbank, in which the female will then lay eggs.
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It has been scientifically proven that the number of eggs in a clutch is directly proportional to the weight of the female, it is generally accepted that there are 1 thousand eggs per 30 kg of the weight of a mature individual. Due to such fecundity, Silurus glanis is capable of becoming a native species of the reservoir in which it spawned for the first time over a period of 50-70 years.
At the end of spawning, the female Silurus glanis leaves its native nest, and all worries: protection, aeration of future offspring, fall on the male. The period of male care for eggs lasts up to 2 weeks, after which fry appear, but they are not yet able to leave the nest, since they are not yet able to feed on their own. The source of nutrition for them is the rest of the protein mass in the caviar bag, from which the fry appeared.
After another 2 weeks, while the fry is in the nest, the male takes care of the offspring. Only after the generation begins to divide into groups and tries to make attempts to independently search for food, and the caring “father” is confident in the strength of the offspring, does he let him swim freely.
Large fish have no enemies, most of the enemies are found on the path of the catfish in its initial stage of growth, while the pike or perch can hunt it. No one threatens the caviar clutch either, because it is constantly under the supervision of an adult. Basically, vast populations of Silurus glanis are declining due to thoughtless human capture, as well as human intervention in the ecosystem of the reservoir.