To observe the appearance and behavior of fish, there is nothing more suitable than an aquarium. Various types of fish can live in aquariums.

Gills

Gills are located on the sides of the head of the fish - special respiratory organs, with the help of which the fish absorbs oxygen contained in the water.

Fish and nests

Some fish build a special house to look after eggs. For example, a male three-spined stickleback arranges a real nest of algae. He guards the nest until fry emerge from the eggs.

Caviar

All fish breed, laying eggs. They toss it in large numbers - from hundreds to thousands of eggs at a time, and then, as a rule, leave them. Only fry will emerge from a small part of the eggs, most of them will be eaten by other inhabitants of the reservoir.

All fish, both small and large, living in saltwater or fresh water, have one feature - the skeleton, which consists of many bones.

Interesting fact: There are fish that can live in both fresh and sea water, for example, salmon and eel. Eel can even be without water for some time.

Moon fish

The fish are large and small, graceful and spherical, like this moon fish, which was so named because of its almost round shape.