Abstract
Nase Chondrostoma nasus L. is one of the most threatened reophilic fish species in Poland. At present it has almost disappeared from the northern and central parts of its range while in the south its abundance has decreased. Protection of the species through closed seasons, catch and size limits has not been sufficient, and active enhancement through stocking is now applied. Developing the technology of hormonally induced spawning and adapting carp pond culture techniques for the rearing of nase enabled substantial enhancement efforts. According to Polish Anglers Association, stocking has increased from 50 000 of hatchlings in 1994 to 840 000 of hatchlings, 568 000 summer and 900 000 autumn juveniles, and 1720 two year‐old fish in 2002. At present the problems to be solved urgently are preserving the genetic diversity of cultured and wild populations, and evaluating stocking effectiveness.