Fish are sensitive underwater inhabitants, so many questions arise regarding their habitat, both in domestic aquarium conditions and in natural wild ones. The organs of smell of fish are able to distinguish between their relatives, the smell of food, as well as the smell of chemicals.
Fish have a scent, they pick up smells underwater in the same way as land animals. It is believed that all fish are divided into two groups, one - fish with a large volume of the olfactory bag and constant circulation of water in it, can distinguish much more odors than fish in which this bag will be small, and, moreover, with an inconsistent flow of water.
Physiology
The main organ of smell in fish is located on the head, it is located inside the nostrils in the segment between the eyes and the mouth. The fish has two nostrils: with the help of one water gets in, and with the help of the other it goes out. Each species of fish has its own arrangement of the organs of smell. It should be noted that, for example, in bony fish, such nostrils are located on both sides of the head.
Notice the flap that separates the fish's nostrils: during movement, this flap helps to push the water. After the water enters the nostrils, it flows further into the structure called the "rose". This entire structure consists of many sensory cells, the approximate density of which is about 500 thousand per 1 square millimeter. The folded structure itself allows you to arrange a large number of cells, but each fish breed has its own number of folds, it can be 9 in some, and up to 90 in others.
Thus, with the help of this receptor, the fish captures smells that cause different emotions in it, for example, it is known that the smell of phenol causes panic in large fish, and in small fish it causes depression of the nervous system and even death.
Smell reaction
It is believed that predators possess a keen sense of smell, for which the sense of smell is vital for finding food. Predatory fish reacts to the smell of blood immediately, for them it is like a "red rag": the receptor is triggered, and the fish quickly finds the source of the smell. Sometimes at a distance of up to 2-5 kilometers.
Many fish secrete so-called mucus, by which other fish can navigate and search for their relatives. But if the mucus was secreted by a wounded fish, then other fish have a startle reaction, and they will swim away from such a smell as far as possible.
Smelly secretions such as pheromones attract fish to each other. From a physiological point of view, they are due to the desire of fish to reproduce. That is why fish perfectly smell pheromones and are found during spawning.
Also, many fish are attracted by the smells of certain oils: hemp, anise, sunflower and mint. Fish are sensitive to amino acids and bile acids, which are contained in products; when they enter the water, they immediately leave behind a fragrant trail, along which the fish is guided.
