Literature sources mention 18 fish species from the Hejő watershed. In order to learn more about the fauna, we studied the brook and its tributaries between 2003–2005. We detected a total of 32 fishspecies, 17 of which are new for the watershed. Most of these are native species (Rutilus rutilus, Leuciscus leuciscus, Leuciscus idus, Aspius as
...pius, Leucaspius delineatus, Gobio albipinnatus, Abramis bjoerkna, Abramis ballerus, Lota lota, Gymnocephalus cernuus, Sander lucioperca), but there are some adventive ones (Pseudorasbora parva, Carassius gibelio, Ameiurus melas, Lepomis gibbosus, Perccottus glenii) and a spontaneously immigrated species as well (Proterorhinus marmoratus). Specific natural values of the watershed are the isolated population of minnow (Phoxinus phoxinus) in Kulcsárvölgyi Brook and the frequently occurring mudminnow (Umbra krameri) in the lower reach of Hejő Brook.
The fish fauna of the River Hernád was examined in 24 sampling sites in summer of 2014. As a result of the survey 31 species were detected of which eight are protected and three are highly protected by law in Hungary. The presence of the adventive tubenose goby (Proterorhinus semilunaris) in the estuary of the Hernád was observed for the firs
...t time by us. The most frequently detected species (with 100% frequency of occurrence, FO) were the chub (Squaliuscephalus), the bitterling (Rhodeusamarus) and the bleak (Alburnusalburnus), in addition the bleak was also the most dominant fish of the river. The hydraulic works have detrimental effect on the number of species and specimens and on the diversity of the fish fauna as well. The natural sections of the River Hernád have the most diverse fish assemblages.