River creature — with silvery belly — found in Russia mountains. See new species (2025)

Walking along the River Thames in the 1800s, it was common to pass people and families on gudgeon-fishing picnics.

The small fish, eaten whole like whitebait or anchovies, was a regular meal in 19th-century England, but their range extends far beyond the nation.

Now, researchers surveying the Caspian Sea Basin, or the network of rivers and streams that flow to the Caspian Sea, in the Ural Mountains of Russia have discovered gudgeons in the mountain rivers and streams — and identified a new species.

The fish were caught by researchers in small nets before being photographed in an aquarium setting and euthanized with clove oil for genetic testing, according to a study published April 22 in the peer-reviewed journal Zoosystematics and Evolution.

The new species of gudgeon is about 3.8 inches long and has a notched lower lip, a trait seen in other species, according to the study.

The fish’s breast is “naked” and lacks scales, except for a few individuals that had a couple of scales toward the throat, researchers said, a trait that sets it apart from known gudgeons.

The animal’s body “is dark olive-brown above, merging into a light silvery underside,” researchers said. “There are large, more or less rounded 6-14 (often 10) blotches on (the sides) located along the (middle of the side).”

The fish also has “moderately long” barbels, or whisker-like fleshy protrusions, from the sides of the mouth, according to the study.

“In the Ural River near Orenburg, the gudgeon spawns from the middle of the twentieth days of April to early or mid-May, but individual spawning specimens are caught throughout the summer,” researchers said.

The species was named Gobio uralensis, or the Ural River gudgeon, literally meaning “lives in the basin of this river” regarding its prevalence in the Ural River system, according to the study.

Ural River gudgeons eat larvae of a specific fly species for the first year of their lives, before expanding their palette to include larvae of other insects, mollusks, plant material and algae, according to the study.

“The gudgeon is especially abundant in the mountain tributaries of the Ural and in its upper reaches, where it is numerous in riffles and sandbanks,” researchers said.

The new species was found in southwestern Russia, near the northwestern border of Kazakhstan.

The research team includes Ilya S. Turbanov, Aleksey A. Bolotovskiy, Oleg N. Artaev, Aleksandr A. Gandlin, Marina A. Levina, Ekaterina D. Vasil’eva and Boris A. Levin.