Around 60 fish species are present in the Danube је an its tributaries in the Djerdap National Park area, which only verifies its richness and diversity. Building the hydroelectric power stations “Djerdap 1“ and “Djerdap 2“ in the Danube ceased the migration flows of Black Sea fish wich spawned in the Danube. There was a change to the chemical properties of water, modification to the river bed configuration so that from a fast river, the Danube in the area of Djerdap National Park was turned into a lake. Therefore, certain Black Sea fish disappeared due to mechanical barriers, and some other disappeared for changed made to the living conditions and concurrently the erruption of such population which belong to alien species –silver carp, amur, Prussian carp which were accidentally or purposefully introduced in the Danube. Most significant fish specias are: catfish (Silurus glanis), perch (Stizostedion lucioperca), yellow walley (Stizostedion volgensis), sterlet (Acipenser ruthenus), breаm (Abramis brama), chub (Leuciscus cephalus), common barbel (Barbus barbus), pike (Esox lucius), asp (Aspius aspius), common roach (Rutilus rutilus), blue bream (Abramis ballerus), vimba bream (Vimbra vimbra). Streber (Zingel streber) and common zingel (Zingel zingel) represent permanently protected species due to their reduced number.
Richness and versatility of fish life of Djerdap are very significant for local population, since fishing has represented the profession of a large number of people ever since the old times and entire families engaged in fishing through generations. Danube fishers used to catch the Black Sea spawning fish, beluga (Huso huso) prior to building the hydroelectric power station, which reached the size even up to 7 m and weight of 1,300 kg, sturgeon (Acipenser guldemstadticolchius) which reached the length even up to 2 m and weight of 50 kg, as well as large samples of sterlet (Acipenser ruthenus) weighing up to 15 kg.