The Morphological Characteristics Of The Danube Ruffe, Gymnocephalus Baloni (Perciformes, Percidae), In The Upper Reaches Of The Dnipro River, Ukraine

In the upper reaches of the Dnipro it was found a Danube ruffe population. It differs from the population of the middle reaches of the Dnipro by a longer caudal peduncle. The Danube ruffe differs from sympatric populations of the common ruffe by 10 features. For a fast and precise identification of these two species, it was proposed to use the height of the membrane between the first and second rays of the anal fin as a percentageto the length of the body.