Leonardo DiCaprio has praised Chester Zoo for its work helping to reintroduce a near-extinct species of fish to its native habitat in Mexico.
The golden skiffa had not been witnessed swimming in its only known home, the Teuchitlan River in central-western Mexico, since the 1990s.
To coincide with Day of the Dead celebrations in Mexico this month, experts from Chester Zoo and Michoacan University of Mexico released 1,200 golden skiffas back into their native river after a conservation breeding programme.
DiCaprio, 48, who has long described himself as an environmentalist, praised the project on Instagram.
The Hollywood actor has spoken at key climate summits, including the signing of the Paris climate agreement in 2016.
The team at Chester, who helped prepare the fish for the wild before they were released, were delighted with the endorsement and replied: "Thank you for sharing this incredible story!"
Golden skiffas were made near-extinct by dam construction, water extraction, pollution and an invasive species in their river.
After numbers plummeted, in 2014 scientists from Michoacan University and fishkeepers from the Goodied Working Group helped restore the water and remove any harmful species that could threaten the fish living there.
Under the breeding programme their numbers rose and they were looked after by experts in the UK and Latin America as the population grew.
Fish placed in pods before heading to Mexico
Chester Zoo placed the fish in floating pods called mesocosms, where they lived for a month to help them adapt to natural conditions before they were taken to Mexico.
Before they were let go, they were tagged so they can be monitored for five years to see how the population increases.
Paul Bamford, regional programme manager for Latin America at Chester Zoo, said: "This project is a great example of how zoos can contribute to conservation in the field through conservation breeding and research.
"By supporting freshwater conservation in Mexico and the ecosystems where the fish live, we're not only protecting biodiversity and the wellbeing of freshwater environments, but also the people and communities that live alongside them."
Omar Dominguez-Dominguez, a professor and researcher from the Michoacan University of Mexico, who is leading the golden skiffia reintroduction, said: "Releasing the golden skiffia at this time is a metaphor for how the species has come back from the dead to return to its home, not for one night, but forever.
"Knowing that universities, zoos and aquarists can come together to fix some of what has been destroyed and return to nature some of what has been lost is an amazing thing."