20 Zlotys Ropucha Paskówka (Bufo calamita)

Part of Poland's long-running animal conservation series, this issue was struck at a moment when the natterjack toad had become a focal point of European amphibian protection efforts — its populations in Poland were already in measurable decline due to wetland drainage and agricultural intensification. The National Bank of Poland began the broader collector series in the mid-1990s, explicitly tying each release to species under domestic environmental pressure.

Mintages for these issues were kept deliberately low, and secondary market premiums have historically exceeded face value by multiples.