Fishes are sensitive underwater inhabitants therefore there is a set of the questions concerning their habitat both in house aquarian conditions, and in natural wild. Organs of smell of fishes are capable to distinguish the relatives, a flavor of food and also a smell of chemicals.
Fishes have a scent, they catch smells under water as well as land animals. It is considered that all fishes are divided into two groups, some - fishes with the large volume of a bag of sense of smell and continuous circulation in it of water, can distinguish much more smells, than fish which will have small this sack, and besides with changeable water flow.
Physiology
The principal organ of sense of smell at fishes is on the head, it is located in nostrils on a piece between eyes and a mouth. At fish two nostrils: by means of one water inside gets, and by means of another comes to light. At each species of fishes the arrangement of organs of smell. It should be noted that, for example, at bony fishes such nostrils are located from two parties on the head.
Pay attention to a shutter which divides nostrils of fish: during the movement such shutter helps to push water. After water gets into nostrils, it comes further to the structure called "rosette". All this structure consists of a set of touch cages which approximate density about 500 thousand on 1 square millimeter. The folded structure allows to arrange a large number of cages, but at each breed of fishes the quantity of folds, it can make and 9 at some, and up to 90 at others. Thus, by means of this receptor the fish catches the smells causing in her different emotions, for example, it is known that the phenol smell in large fishes causes panic, and in small - oppression of nervous system and even death.
Reaction to a smell
It is considered that predators to which the sense of smell is vital for search of food possess a sharp scent. Predatory fish reacts to a blood smell at once, for them it as "a red rag": the receptor works, and fish quickly finds a smell source. Sometimes at distance up to 2-5 kilometers. Many fishes emit so-called slime on which other small fishes can be guided and look for the relatives. But if slime was emitted by the wounded small fish, then other fishes have a reaction of a fright, and they will departure from such smell as it is possible further. Such odorous allocations as pheromones, attract fishes to each other. They from the physiological point of view are caused by aspiration of fishes to reproduction. For this reason fishes perfectly catch a smell of pheromones and meet on spawning. Also many fishes are attracted by smells of some oils: hempy, anisic, sunflower and mint. Fishes are sensitive to amino acids and bilious acids which contain in products, at hit in water they at once reserve a fragrant loop on which fish is guided.