New efforts for saving the thermal rudd

The thermal rudd (Scardinius racovitzai) is an endemic and Pannonian relict fish species once confined only to Lake Pețea in Băile 1 Mai (Romania). After habitat destruction, it is now classified as Extinct in the Wild (EW) by the International Union for Conservation of Nature (IUCN).

Severe thermal water loss in 2013–2014 led to emergency rescue of the endemic fauna by Muzeul Țării Crișurilor (Oradea) back then, namely of the thermal snail (Melanopsis pareysii) and the thermal rudd . Captive breeding of the thermal rudd first succeeded in 2014, during an international program supported by the Mohamed bin Zayed Species Conservation Fund (Abu Dhabi, United Arab Emirates), with juveniles introduced to the original site and distributed to a few zoos and public aquaria. But as the lake has since completely dried out, ex situ conservation remains critical. In 2024, an international collaboration between Muzeul Țării Crișurilor, the Museum Complex of Natural Sciences ”Răsvan Angheluță” Galați, the Schönbrunn Zoo (Vienna), and the Hungarian University of Agriculture and Life Sciences (Gödöllő) launched a renewed effort to produce viable offspring from existing broodstock. As part of this, both hormonally and temperature induced spawning was conducted at the Museum’s Vivarium in Oradea, once again yielding fertilized eggs and developing embryos in spring 2025. The juveniles from the propagation trial are being reared in the Vivarium, like the previous generations since 2014. This work contributes to the species’ long-term conservation. The program is supported again by the Mohamed bin Zayed Species Conservation Fund.