The Caspian trout (''Salmo caspius'') is a disputed

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

of fish in the family Salmonidae. It is native to

Eurasia Eurasia (, ) is the largest continental area on Earth, comprising all of Europe and Asia. Primarily in the Northern and Eastern Hemispheres, it spans from the British Isles and the Iberian Peninsula in the west to the Japanese archipelago a ...

, where it occurs only in the southern

Caspian Sea The Caspian Sea is the world's largest inland body of water, often described as the world's largest lake or a full-fledged sea. An endorheic basin, it lies between Europe and Asia; east of the Caucasus, west of the broad steppe of Central Asia ...

basin. It reaches 25 cm (9.8 inches) in

standard length Fish measurement is the measuring of individual fish and various parts of their anatomies. These data are used in many areas of ichthyology, including taxonomy and fisheries biology. Overall length * Standard length (SL) is the length of a fish m ...

. While historically considered a distinct species, recent evidence suggests that the Caspian trout, as well as the

Black Sea salmon The Black Sea salmon (''Salmo labrax'') is a fairly small species of salmon, at about long on average and rarely reaching over . It inhabits the northern Black Sea coasts and inflowing rivers. There are anadromous, lacustrine and resident river ...

(''Salmo labrax'') and the

Abant trout The brown trout (''Salmo trutta'') is a European species of salmonid fish that has been widely introduced into suitable environments globally. It includes purely freshwater populations, referred to as the riverine ecotype, ''Salmo trutta'' morp ...

(''Salmo abanticus'') are not distinct species but are instead morphs of the

brown trout The brown trout (''Salmo trutta'') is a European species of salmonid fish that has been widely introduced into suitable environments globally. It includes purely freshwater populations, referred to as the riverine ecotype, ''Salmo trutta'' morph ...

(''Salmo trutta'').Kalayci, G., Ozturk, R.C., Capkin, E., & Altinok, I. (2018). Genetic and molecular evidence that brown trout Salmo trutta belonging to the Danubian lineage are a single biological species. ''Journal of fish biology, 93 5'', 792-804 .

References

{{Taxonbar, from=Q14303230 Fish described in 1877 Salmo