The laterally compressed body of the fish has a streamlined shape, which reduces the resistance of the water during their movement. In it, you can distinguish the head, body and tail.
Fish have limbs – unpaired and paired fins.
Unpaired are dorsal, caudal, and anal (caudal).
Paired fins (limbs) are located below the sides: front – pectoral and rear – abdominal.
The fish skin is two-layered, thin, slimy, covered with bone scales. The scales are constantly growing, and annual rings are formed on it, by which you can determine the age of the fish.
The mucus secreted by the skin glands of the fish allows it to slide and reduces friction during swimming.
On the sides of the fish’s body there are lateral line organs – channels lying in the skin under the scales, at the bottom of which there are sensitive cells that perceive water vibrations. With the help of the lateral line organ, the fish perceives the direction of the current and water pressure, the presence of obstacles, and sound vibrations.
On the head in front there is a mouth, with which the fish captures food and draws in water necessary for breathing.
Above the mouth, there are nostrils that open into the olfactory organs, with the help of which the fish perceives the smells of substances dissolved in water.
The eyes of fish are rather large, they have a flat cornea, a spherical lens. No century. Fish can see at close range and distinguish colors.
The hearing organs (inner ear) are located on the sides of the head inside the skull.
Near the inner ear is the organ of balance, thanks to which the fish senses the position of its body, moving up and down.