The Řežabinec National Natural Monument is located near Ražice in South Bohemia (Czech Republic). It consists of a pond created on the site of wetlands in the former bed of the Otava River, as well as pools and wetlands formed by the flooding of pits after mining. During surveys in 2014 and 2024, a total of 24 species of aquatic molluscs (17 gastropods and 7 bivalves) were found. The most important find was the pea mussel Euglesa pseudosphaerium. Its large populations were found here during both surveys in the wetlands around the pond and in the pools and wetlands east of it. This species is rare and critically endangered in the Czech Republic and occurs in shallow and overgrown pools. It has not been recorded anywhere else in South Bohemia. In the 10 years between the two surveys, there were only minor changes in the composition of mollusc assemblages.