The marble trout is found in only a handful of drainages and rivers of the Adriatic basin in (going from north to south) Italy, Slovenia, Croatia, Bosnia and Herzegovina, and Montenegro, while in Albania, the species is considered most likely extirpated.

In Italy, marble trout inhabits left tributaries of the upper northwestern reaches of the Po River, and Italian northeastern sub-Alpine region's direct Adriatic watersheds, namely the Adige, the Brenta, the Piave, the Tagliamento, and the Livenza; in shared Slovenia and Italy drainage of the Soča with Natisone; in shared Bosnia and Herzegovina and Croatia drainage of the Neretva river, and in shared Montenegro and Albania drainage of the Morača with Zeta river, and the tributary Cem (Cijevna).

It suffers numerous threats to its existence throughout its range, these include hybridisation with foreign trout species stocked for angling, water extraction, and pollution.

In Bosnia and Herzegovina, its main threats are habitat loss (habitat destruction) due to construction of five large dams on the Neretva River and plans for construction of several new dams on the upper course of the Neretva, water pollution, overfishing (sportfishing, food, including poaching), and hybridisation with introduced species of trout.

[10] The capture of a 955 mm (37.6 in), 10,220 g (22 lb 8 oz) specimen from the Eastern Adriatic Sea off Igrane by a commercial spearfisher supports this hypothesis.