Despite the fact that fish breathe with gills, most of them have a nose



Much of the fish are not too rely on odor in aqueous medium. However, many of them have a nose. He has no connection with the mouth and did not play a role in breathing. Generally, fish nose consists of a pair of small nostrils at the front or side of the head.

At the most primitive species have only one nostril. Some predatory fish need a nose to smell prey. Others use it to navigate in water. For example, salmon use their excellent sense of smell to determine a stream where he was born, and when it comes time to get back into it and to give birth to their own offspring.

via factroom.ru