Prague Zoo Releases Critically Endangered Crucian Carp in Prague’s Michle District
21. 07. 2025
Prague Zoo organised this year’s first release of crucian carp. It took place in the Prague district of Michle. Approximately 250 small fish that had been bred at Prague Zoo were released into the Interlov retention pond on the edge of Kunratický Forest. This critically endangered species, which disappeared from the Czech countryside mainly due to the loss of its natural habitat and competition from the invasive Prussian carp, has been returning to Czech water courses since 2022. Today’s release makes it 26 locations where Prague Zoo and its partners have released the carp. These locations are now home to tens of thousands of fish.
Catching young crucian carp in a pond at Prague Zoo and getting them ready to be taken to Michle, Prague. Photo: Petr Hamerník, Prague Zoo
Miroslav Bobek, Prague Zoo’s director, said, “The return of the crucian carp to the Czech countryside is one of Prague Zoo’s key initiatives to protect our biodiversity. Once a common fish in our pools and village ponds, it is now on the verge of extinction. By reintroducing or introducing it into suitable habitats, we are helping both the carp itself to survive, as well as creating a refuge for endangered amphibians as its presence also contributes to healthy ecosystems that keep water in the landscape.”
Just a few decades ago, the crucian carp was one of the most common fish in the Czech Republic. However, the turn of the millennium saw its situation change and today it is a critically endangered species. There are various reasons for this, but there are two that have had a significant impact.
The first factor in the rapid drop in crucian carp numbers is habitat loss. Originally, the crucian carp was found in the lower reaches of rivers, dead ends or overgrown pools. However, these aquatic refuges gradually disappeared from the landscape due to changes in farming. Flooded quarries, fire water reservoirs and other forgotten water areas remained the only hope for finding any surviving fish.
An adult crucian carp. It differs from its greatest competitor, the Prussian carp, in its colour and the shape of its dorsal fin. It can be easily distinguished from the common carp by the absence of barbels. Photo: Petr Hamerník, Prague Zoo
The last nail in the coffin for the crucian carp was its Asian relative, the Prussian carp. Introduced in the 1960s, it has displaced ‘our’ crucian carp from the handful of locations where it remained. Not only does it show similar resilience, it also reproduces rapidly through gynogenesis, a form of asexual reproduction. This makes it a significant competitor for the crucian carp. Moreover, both carp can also interbreed and create hybrid populations.
A few years ago, Prague Zoo made the decision to save the crucian carp. It was necessary to find genetically suitable fish, a place to breed them, locations suitable for their subsequent release, and to educate the public. The project is accompanied by a comprehensive press kit where you can find photos and videos to download: https://www.zoopraha.cz/vse-o-zoo/press/presskity/15579-karas-2025
Petr Velenský, Prague Zoo’s curator of reptiles, amphibians and fish, releases critically endangered crucian carp into the Interlov retention pond in Michle, Prague. Photo: Petr Hamerník, Prague Zoo
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