The life of nature is amazing, complex, interesting and diverse in all its manifestations. The love of nature makes us reproduce "a piece of nature" in a small vessel - an aquarium. A properly equipped aquarium contains a certain number of fish and plants suitable for each other in terms of content: temperature, lighting, "biological equilibrium" .. In the last decade, the art of keeping fish has risen to a higher scientific level. This is manifested in the higher equipment of aquariums of all kinds of techniques and devices, as well as in a more meaningful approach to the processes occurring in aquariums when maintaining and breeding fish. The book describes fish that live well in aquarium conditions and most of them reproduce. The book is designed for biologists, as well as for wide circles of amateur aquarists .