Veliki vretenac (Zingel zingel)
Ova rijetka, autohtona vrsta uobičajeno naraste u duljinu 15 – 20 cm. Zadržava se u plitkim do srednje dubokim vodotocima, s pješčanim i šljunkovitim dnom Dunava, Drave, Mure i Kupe. Noću, kada se približava obali hrani se beskralježnjacima i ličinkama drugih riba. Ekologija ove vrste nije dovoljno poznata. Zbog oštrih i hrapavih ljusaka, oštrih peraja i trnova po škržnom poklopcu jedini su mu predatori štuka i čovjek.
Uzrok ugroženosti je onečišćenje i pregradnja vodotoka čime se usporava brzina vodotoka i povećava taloženje mulja što dovodi do smanjenja količine kisika na koju je ova vrsta jako osjetljiva.
Zingel (Zingel zingel)
This rare, autochthonous species usually grows to a length of 15 – 20 cm. It stays in shallow to medium-deep watercourses, with sandy and gravelly bottoms of the Danube, Drava, Mura and Kupa. It has a spindle-shaped, wide torso in the front part, a long and flat head and a narrow peduncle. The back is brown to greenish-brown, the sides are yellowish or greenish-yellow, and the belly is light. The scattered spots are dark brown, and the marbling is stretched between slanted, partially erased, brown-black thick lines. At the edge of the brownish gill cover there is a spine. At night, when it comes closer the shore, it feeds on invertebrates and larvae of other fish. The ecology of this species is not well known. Because of its sharp and rough scales, sharp fins and spines on the gill cover, its only predators are pike and man.
The cause of endangerment is the pollution and water barriers, which slow down the speed of watercourses and increases the deposition of mud, which leads to a reduction in the amount of oxygen to which this species is very sensitive.