Marble trout in shallow water.
Under natural conditions, the length of the fish varies from 30 to 70 cm, but there were exceptions. So in Slovenia a dead individual was found, whose length was 117 cm with a mass of 24 kg, and the largest live trout caught reached 120 cm with a mass of 22.5 kg [1] [2] . The maximum body weight is 50 kg [3] .
This type of trout is distinguished by the large size of its head, the length of which is 22-25% of the total body length, which is why in Bosnia and Herzegovina it is called “Glavatica” (“Glava” - head).
The body is silver or olive green with brown lines scattered throughout the body, forming a characteristic marble pattern. In juveniles longer than 6 cm, there are already no mottled spots. Red spots that are absent in some individuals pass along the lateral line; brownish spots or lines on the gill cover [3] .
Distributed in the north of the Adriatic basin, found only in northern Italy in the northern tributaries of the Po river, in the rivers Adige , Brenta , Piave , Tagliamento ; in Slovenia ( Socha River ), in Croatia and Bosnia and Herzogovina ( Neretva River) and in the Moraca River ( Montenegro ) [4] [5] and in the south of Switzerland [6] . Freshwater fish. It inhabits cold rivers and lakes in mountainous and foothill areas, in which the water temperature in the summer months does not exceed 15 ° C.
Males reach maturity in the fourth year of life (3+), in a female a year later (4+). Spawn during November and December. It does not spawn migrations and moves only over short distances. Individuals wandering in the lakes go to spawn in the tributaries of the lakes to spawn. Larvae hatch after 45 days, and juveniles switch to active feeding 59–63 days after fertilization of eggs at a temperature of 10 ° C [3] .
The juveniles feed on various invertebrates and insects, and adult individuals are predators and the basis of their diet is fish.
The number of this species of trout is small, since the beginning of the XX century the number of individuals has been steadily decreasing. Today, marble trout is bred for both food and sport fishing .
