Don ruff

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Don ruff
Systematics
Perch relatives (Percomorphaceae)
Order : Perch-like (Perciformes)
Subordination : Percoidei
Family : Real perch (Percidae)
Genre : Gymnocephalus
Type : Don ruff
Scientific name
Gymnocephalus acerina
( JF Gmelin , 1789)

The Don ruff ( Gymnocephalus acerina ) is a real bony fish from the family of real perch .

features

The Don ruff is less high-backed than the species of the (traditional) subgenus Acerina (with Gymnocephalus (Acerina) cernua and Gymnocephalus (Acerina) baloni ). It has smaller scales and more dorsal spines. It becomes 25 cm long and is silvery yellow-gray, with irregularly distributed round dark spots of different sizes. D1 with 17–19 spines and three rows of black spots. D2 I / 13-15, A II / 7-8. These fins and the caudal fin are barely punctured. 50–54 lateral line scales and 4–5 unperforated on the slender caudal fin stalk.

Occurrence

The home of the Don ruff ( Russian носарь or бирючок) is limited to the rivers Don , Dnieper , Dniester , Southern Bug and Kuban , which flow into the Black Sea - that is, to Ukrainian and Moldavian rivers, only in the Dnieper and its tributary Pripyat it also reaches Belarus . Lost specimens can e.g. B. appear in the Danube Delta. It is not common anywhere and has no economic significance. The news from days gone by that it was very tasty is still very much alive in the Ukrainian population.

Way of life

Although this perch is also found in still water and lakes, it prefers sandy stretches of larger rivers, also with stronger currents (but it also occurs over gravel) and lives socially on benthos (insect larvae, crabs, worms, mollusks, hardly any fish). It is crepuscular and also diurnal. In autumn it retreats in larger swarms into deeper water and survives here inactive during the winter. He does not make a spawning migration, but spawns from a size of approx. 13 cm (i.e. at the age of 2 or 3 years) in spring in the swarm in the current over sand or gravel, where the sinking eggs stick. At 14 °, egg development takes ten days, but the larvae, which are then approx. 4.5 mm long, remain inactive until the yolk is used up.

Systematics

The Don ruff differs more clearly from other species of the genus Gymnocephalus than they do from one another, so that, according to Holčík and Hensel (1974), together with the Schrätzer ( Gymnocephalus schraetser ) it represents the subgenus Gymnocephalus , which was compared to the subgenus Acerina - but the most recent genetic Studies do not support the two morphological subgenera, so their existence is currently unclear.

Individual evidence

  1. ↑ The species name probably refers to the eyes that (in contrast to zander, for example ) have no tapetum lucidum (for "shining" [cat] eyes): α-κηρίνη "without wax light". Another explanation would be (Latin) acer ("rough") + suffix -inus.
  2. ^ Matthias F. Geiger and Ulrich K. Schliewen: Gymnocephalus ambriaelacus, a new species of ruffe from Lake Ammersee, southern Germany (Teleostei, Perciformes, Percidae). Spixiana, 33, pp. 119-137, 2010

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