Marble Trout

Marble trout has evolved from the Brown trout. It is believed that Marble trout was the only trout species in Slovenia’s western river until fishermen introduced other species into these rivers. This has become a problem when they started introducing Brown trout into the rivers of Mediterranean basin a hundred years ago, because of the genetic similarities between the two species, it came to hybridisation and the pure Marble trout almost disappeared. When realising the mistake, Slovenian fishing organisations tried everything to bring back the legendary genetically pure marble trout and by the end of the 20th century they succeeded. In tributaries of the river Soča they found pure Marble trouts, which were living in isolation and haven’t yet crossed path with Brown trout. With repopulation and careful supervision, pure Marble trout returned and resides in River Soča and some other rivers around it. Rainbow trout and Grayling, who also live in the Soča river, are not able to breed with marble trout so they do not pose any danger to the Marble trout.

Marble trout has cylindrical shaped long, lean body. For it’s very large head, who takes up around ¼ of the entire body, it has pretty small eyes. Dorsal fin is also relatively short. It has strong mouth with many sharp teeth. Males can be distinguished from females by the conclusion of the lower jaw, which is directed downwards in males and is straight in females. Marble trout has distinct body pattern, with the olive-green colour being dominant over black, which we can see on top of the head and upper side of the body. Downward from the head to the belly, green mixes with light black, the two colors interweaving along the way, creating a special, marble-like pattern that is distinctive for this species. Hence the name Marble trout (Salmo marmoratus in Latin). Marble trout also has some greenish-black dots, easily seen on the dorsal fin. In females, red dots can also be spotted. Marble trout reaches maturity in the 4th year. Spawning time is relatively short, usually from start of December until the start/ middle of January. The most active spawning time is in the evening and during the night.

Young Marble trouts mostly eat algae and plants found on the river bed, they also feed on insects. When they grow bigger, Marble trouts start feeding with other fish.

Marble trouts live in cold, fast flowing rivers, but they can also be found in the lakes. Fish is endemic; it only lives in the waters of the Mediterranean basin. It can be found in Slovenia, some Balkan countries, Austria and a few Italian rivers. They are the most common in middle flow of the Soča river and it’s tributaries. Special subspecies resides in river Idrijca. It has very specific pigmentation that differs from the one from Soča river. Marble trout reaches maturity in the 4th year. Spawning time is relatively short, usually from start of December until the start/ middle of January. The most active spawning time is in the evening and during the night.

In Slovenia one can fish for Marble trout from April 1st to September 30th. Because Marble trout grows bigger than other trout species and is also more powerful, it presents a challenge to all the fishermen out there who come to Slovenia especially only to catch this alpine beauty.