The main feature of this fish is represented by the significant differences existing among the specimens, which has often caused confusion about its name. As a matter of fact, it can be fully scaled, have a smooth coat with a few giant scales, "the mirrors", or be completely unscaled, but it always belongs to the same breed. Omnivorous, it can also grow to more than one meter. It lives in all the continents and at all latitudes, except Scotland and Scandinavia.
Despite it is a minor commercial species in Italy, at a global level is one of the most bred fish. It lives in rivers and lakes, in hot and cold waters. It is one of the best easy-fitting fish species.