Rare Fish and River Restoration on the Upper Rába

The upper Rába still offers a home to rare, protected fish. Recent surveys explored where they live, where they can find food and spawn, and what could help them move more freely along the river.

Natural river habitat along the upper Rába in Hungary, with gravel banks, driftwood and riverside trees. — The upper Rába River in Hungary, where natural habitats provide important spawning and feeding grounds for native fish.

Kessler’s gudgeon (Romanogobio kesslerii) and the Danube streber (Zingel streber) are among the fish living in the upper Rába. Researchers confirmed the presence of both strictly protected species while surveying the river between Rábagyarmat and Magyarlak, Hungary. This stretch also provides important habitat for migratory species such as nase (Chondrostoma nasus) and barbel (Barbus barbus).

Kessler’s gudgeon (Romanogobio kesslerii), a strictly protected fish species, held in a researcher's hand. — Kessler’s gudgeon (Romanogobio kesslerii), one of the rare, strictly protected fish species found in the upper Rába. © Tibor Erös

Danube streber (Zingel streber), a strictly protected fish species, resting on a researcher's hand. — The strictly protected Danube streber (Zingel streber), recorded during fish surveys on the upper Rába. © Tibor Erös

The fieldwork brought together fish ecologists from the HUN-REN Balaton Limnological Research Institute (BLRI) and experts from the Őrség National Park Directorate. As two Hungarian demo site partners in the DANUBElifelines Horizon project, they are working together to understand the river’s fish communities and the habitats that support them.

Where do fish find the conditions they need?

Along the upper Rába, the team found a variety of habitats, including short stretches that could provide valuable places for native fish to spawn and feed.

Fish researchers wading through the upper Rába River during an ecological field survey. — Fieldwork on the upper Rába: researchers investigating fish communities and river habitats.

Understanding what makes these places suitable is an important part of deciding where river restoration could bring the greatest benefits. In Hungary, the project’s research covers sites along both the Danube and the Rába. Scientists compare degraded river sections with those that remain close to natural conditions, looking at the habitat features that help fish spawn, feed and survive.

These comparisons can help identify which conditions matter for fish and where restoration efforts would be most useful.

Helping fish reach suitable habitats

Finding suitable habitat is only part of the story. Fish also need to be able to reach it.

Two researchers surveying fish habitats in the upper Rába River in Hungary. — Researchers surveying fish habitats along the upper Rába River in Hungary.

Small hydropower installations have restricted fish migration along the Rába. At Körmend and Magyarlak, effective fish passage facilities are still lacking, although their construction is expected in the coming years. Improving passage at these locations would help fish move more freely along the river and access the habitats they need at different stages of their lives.

By combining BLRI’s fish ecology expertise with the local knowledge of Őrség National Park specialists, the surveys are building a clearer picture of the habitats that sustain the river’s biodiversity. Their findings can help guide future restoration on the Rába.

Consent

The upper Rába still offers a home to rare, protected fish. Recent surveys explored where they live, where they can find food and spawn, and what could help them move more freely along the river.

Where do fish find the conditions they need?

Helping fish reach suitable habitats

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