The marble trout (salmo trutta marmoratus) it is an endemic fish of the Adriatic river system. From other trout species differs by its characteristic marble pattern and disproportionately large head. Because of its high growth capacity the marble trout can reach exceptional sizes. The largest specimen caught while fly fishing is from Soča river and was 48 inches (122 cm) long and 49.5 pounds (22.5 kg) in weight. But fish as big as that one are more of an exception than the rule. An average size in the main rivers ranges from 15 to 25 inches (40-65 cm), while trouts are smaller in the tributaries, but it depends on the size of the stream. Without a doubt and regardless of the size the marble trout is the most desirable fly fishing catch in our waters.
Also known as the lady of the stream, the grayling (Thymallus thymallus) is an endemic salmonid species to our rivers. It has an elegant body in gray to gray-yellow color with a few black dots on the body and a characteristic dorsal fin.
It can grown up to 25 inches (60 cm) in length and reach up to 9 pounds (4kg). They prefers clean cold waters where they feed on vegetable matter, aquatic insects and, despite having smaller soft mouth, they occasionally eat small fish.
Native to Danube river basin, the brown trout (Salmo trutta) is a well-represented fish species in Slovenian waters. It has been introduced to our waters and began to breed with marble trout, resulting in crossbreed species. Its habitat is cold water, rich with oxygen. Full grown fish can reach a length of over 32 inches (80 cm) and a weight of up to 17 pounds (8 kg).
Non native to our rivers, the rainbow trout (Oncorhynchus mykiss) has been introduced to our waters with intent to diversify sport fishing. Rainbow trout has quickly become accustomed to the new environment, now they naturally spawn and grow in some of our rivers. It can grow up to 35 inches (90 cm) in length and weigh 22 pounds (10 kg).