An endangered native fish is set to benefit from a barrier to protect it from bigger, introduced fish in Central Otago.

A one-metre high concrete weir was installed in Thomsons Creek near Omakau, in the Manuherikia River catchment, using government and regional council funding.

Six endangered Central Otago roundhead galaxias found in the stomach of a brown trout (Photo: Daniel Jack).

Its purpose was to keep trout and perch downstream of the habitat of Central Otago roundhead Galaxias, a kind of non-migratory whitebait.

Any introduced predator fish already living above the weir would be relocated downstream.

The regional council said it was an important project, as all of Otago's non-migratory galaxiid species were threatened with extinction.