What is a fish? River and sea fish (photo)

In this article we will consider the question of what kind of fish is. It should be clarified immediately that the word "fish" in the meaning of "dish" will not be discussed here. Only live fish, that is, a creature that lives in an aquatic environment, is of interest to us in this case. This is a superclass of aquatic vertebrates, the bulk of which is dominated by gill respiration and the lack of feeding offspring of milk with special glands.

Separation of fish by habitat

These creatures in this vein should be considered according to the main feature - whether they belong to freshwater, brackish water, or they need salty water for life. As you can see, the question of what kind of fish is, you can answer in detail. In the first case, it is the one that lives exclusively in salty sea or ocean water. Still there are such breeds that perfectly survive in both fresh and salty environments. This is because the optimal for them is a brackish liquid, that is, in which the ratio of fresh water and salt is in the proportion of about 1000: 1.

Inhabitants of the seas and oceans

If the reader is interested in what kind of fish is in the seas and oceans, then this far from complete list is the answer:

• Tiger shark;
• flounder;
• herring;
• salmon;
• Sea pikeperch;
• halibut;
• Sea dog;
• tuna;
• Butterfly fish;
• sea Horse;
• Sea needles;
• Lionfish;
• Molva - sea pike;
• Moray eels;
• Electric eel;
• Sea small-smelt smelt;
• swordfish;
• Fish-hedgehog;
• The sea duck, or the European angler;
• Triggerfish;
• sea bass;
• Capelin;
• sprat;
• Saury;
• hake;
• Sea bream;
• Sailing ship;
• Flying fish ;
• catfish;
• clown fish;
• Cyan lucian;
• Notothenia;
• Golden spar, or redfin;
• Fish-noodles;
• Manta, or giant sea devil.

Already by name, you can determine how different ocean and sea fish are. Photos of some species will only confirm this fact.

Habitat of freshwater fish

On the question of what kind of fish is, you answered: "Freshwater"? And what is fresh water?

It should immediately be answered that an aqueous medium that is practically free of salts can be called fresh. Usually such is considered running water, that is, rivers. But many lakes fall into this category. It is no secret that part of freshwater fish for commercial purposes is artificially cultivated in ponds and aryks created by human hands. By the way, considering the photo of river fish living in natural conditions, and comparing them with pictures of those that were born and grown in man-made reservoirs, it is practically impossible to notice the difference.

And, what's really interesting, even marshes can serve as habitats for some species of freshwater fish.

Inhabitants of rivers

Many of the supraclasses of aquatic vertebrates, not feeding offspring with milk (refer to freshwater), live in rivers. Their list is also quite large. In Russia, the most common are the following:

• zander;
• perch;
• Bersh;
• ruff;
• pike;
• bream;
• roach;
• Chop;
• White-eyed;
• carp;
• chub;
• Crucian carp;
• Gushers;
• carp;
• tench;
• Asp;
• Red-rind;
• Chekhon;
• The subacute;
• Beetwort;
• bleak;
• ide;
• gudgeon;
• Carp;
• Cupid white ;
• Som;
• acne;
• Snakeheads;
• loach;
• burbot;
• Char;
• salmon;
• sterlet;
• trout;
• grayling;
• umber;
• Carp and others.

Photos of river fish are incredibly beautiful. Fishermen often take pictures of their trophies, they are extremely proud of them. Unfortunately, river live fish in the natural habitat is poorly represented in photographs.

Who lives in the swamps?

Interesting in this regard, crucian carp. Although it can comfortably live in rivers and lakes, ichthyologists still think that it is extremely difficult to meet it in clean mountain water bodies. But in the lowland marshy lakes and directly in the swamps, it feels just fine.

Many anglers say that often on a hook in overgrown muddy pools they come across sazans, carp, bulls, a line and eels. Som, too, albeit occasionally, but found here.

Separation of fish species by feeding method

All river and sea fish, as well as aquarium decorative, are classified based on how they eat. Some of these animals should be attributed to predators, since their main diet is smaller fish, often even fry of the same species. Many predators do not disdain mollusks, caviar, carrion.

To date, there have been tragic cases of attacks on humans of the largest bloodthirsty fishes - sharks. There are legends in the people about how dangerous catfish and big pikes are for humans. Allegedly, some large specimens of these species can drag a child or a thin woman deep into the reservoir, where they straighten their victims. Or, they say, they mercilessly bite off the limbs of the unhappy during bathing. However, there were no reliable facts of this.

But the sea "sisters" of river pike - barracuda - are capable of terrible crimes. They match the ruthless moray eels, about whom it is said that in ancient times among the Greeks they were widespread aquarium fish, which their owners used as a tool for the execution of those who were disagreeable and guilty of anything.

Chill hearts are stories about piranhas, chimeras, tiger fish and giant guperah - these are also sea fish. The photos of the above-mentioned killer fish look quite intimidating. Nevertheless, it is worth noting that most predators among fish represent a danger only for smaller inhabitants of reservoirs. To these include burbot, catfish, trout, pike, eel, whitefish, asp, borsch, perch, pike perch, grayling, which in large numbers live in Russian rivers.

Bulls, loaches, fir-trees, carp, line, roach, fish, blue, barbel, yazi, spikes, stickers, carp, rots, minnows, breams, crucian carp, bumblebee, verhovki, white-eyed, cupids, chubby, ruff, reddish, Pelagi, vendace and some other freshwater fish.

Differences in the mode of reproduction

Most living creatures of the supra-vertebrate under consideration are spawning. And here there is a division, because some species use external fertilization. This occurs when the female throws unfertilized eggs into the water, and the males, belonging to the same species of fish, release a white liquid with spermatozoa - milk, into the fertile medium.

There are fish related to ovoviviparous. That is, fertilization takes place inside the body of the female. It turns out that the light is already almost formed malok. These include some stingrays, sharks, eagles, buckwheat, sea bass, carp-toothed and some others.

Some live aquarium fish are also viviparous, the photos of which are presented in the article. This, for example, guppies and swordsmen.

Reproduction of salmon and sturgeon

Salmonid and sturgeon (the so-called red fish) belong to the spawners. A photo of a male salmon before spawning vividly demonstrates how much its appearance changes before this important period in life. The emerging peculiar hump on the back gave the name to one of the salmon species - pink salmon. The jaws of the fish curl in a hook, their body acquires a bright, even evocative color.

Interestingly, most species of red fish (sockeye salmon, pink salmon, chum, and others) are brackish water. They are born in fresh rivers, then swimming in the marine environment. To spawn, males and females move against the current back to the place of their appearance. A very large number of salmon representatives die during this period, and not reaching the goal: some due to natural factors, and others - because of poaching. After spawning, almost all individuals of both sexes die. Although ichthyologists found several exceptions to this rule, it was possible to register several females that came to spawn five or even seven times.

Sturgeon fishes are also roamed . The names of some species of this valuable commercial breed are known to practically everyone. This stellate sturgeon, sturgeon, thorn, beluga, sterlet and some others.

Aquarium fish

The photos of these vertebrates attract the attention of even those people who are absolutely indifferent to the ichthyology and do not feel like starting such original pets. The brightness of coloring, the unusualness of their appearance play a major role in this.

However, for those who are interested in the underwater world and its inhabitants, aquarium fish can become a real practical tool. Observing them, studying their habits, one can distinguish all the main gradations of this natural superclass of vertebrates.

As well as all fish, these pets, contained in aquariums, are divided into freshwater, brackish and marine.

There are also notorious predators attacking other inhabitants not from hunger, but because such is their natural essence. This example is piranhas and decorative sharks. Along with them, there are insectivorous fish, as well as those that prefer worms, bloodworms, algae, etc.

Aquarium fish are subdivided into spawning and viviparous. Most, of course, refer to those who throw caviar and milk into the water.

Briefly about the main thing ...

Watching the life of fish, a person makes important conclusions for himself: in nature everything is interconnected, everything depends on one another. And man - this is one of the links in the chain, for the integrity of which he is responsible.