Common bleak

The common bleak (Alburnus alburnus) is a small freshwater coarse fish of the cyprinid family.[1]

Bleak
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Cypriniformes
Family: Cyprinidae
Subfamily: Leuciscinae
Genus: Alburnus
Species:
A. alburnus
Binomial name
Alburnus alburnus
Synonyms
  • Cyprinus alburnus Linnaeus, 1758
  • Abramis alburnus (Linnaeus, 1758)
  • Leuciscus alburnus (Linnaeus, 1758)
  • Aspius ochrodon Fitzinger, 1832
  • Aspius alburnoides Selys-longchamps, 1842
  • Alburnus acutus Heckel, 1843
  • Alburnus obtusus Heckel, 1843
  • Alburnus lucidus Heckel, 1843
  • Leuciscus dolabratus Valenciennes, 1844
  • Alburnus strigio Bonaparte, 1845
  • Alburnus ausonii Bonaparte, 1845
  • Alburnus gracilis Bonaparte, 1845
  • Alburnus fracchia Bonaparte, 1845
  • Alburnus avola Bonaparte, 1846
  • Alburnus fracchia Heckel & Kner, 1858
  • Alburnus breviceps Heckel & Kner, 1858
  • Alburnus scoranzoides Heckel & Kner, 1858
  • Alburnus fabraei Blanchard, 1866
  • Alburnus mirandella Blanchard, 1866
  • Alburnus linnei Malm, 1877
  • Alburnus arquatus Fatio, 1882
  • Alburnus maximus (Fatio, 1882)

Description

The body of the bleak is elongated and flat. The head is pointed and the relatively small mouth is turned upwards. The anal fin is long and has 18-23 fin rays. The lateral line is complete. The bleak has a shiny silvery colour, and the fins are pointed and colourless. Its maximum length is about 25 cm (10 in).

In Europe, the bleak can easily be confused with many other species. In England, young common bream and silver bream can be confused with young bleak, though the pointed, upward-turned mouth of the bleak is already distinctive at young stages. Young roach and ruffe have wider bodies and short anal fins.

Occurrence

The bleak occurs in Europe and Western Asia: north of the Caucasus, Pyrenees, and Alps, and eastward toward the Volga basin in northern Iran and north-western Turkey. It is absent from Iberian and Apennine peninsulas, from the rivers of Adriatic watershed on the Balkans and most of British Isles except southeast England. It is locally introduced in Spain, Portugal, and Italy, though.

The shiny and pearly colours on the head of a bleak in direct sunlight

Ecology

The bleak lives in great schools and feeds upon small molluscs, insects that fall in the water, insect larvae, worms, small shellfish, and plant detritus. It is found in streams and lakes. The bleak prefers open waters and is found in large numbers where an inflow of food from pumping stations or behind weirs occurs.

Spawning

The bleak spawns near the shore in shallow waters. Some are found in deep water. The substrate is not important.

Importance

The bleak is an important food source for predatory fish. It is more sensitive to pollution than other cyprinids, which might explain the decline in north-western Europe.

Uses

Bleak are used as bait for sport-fishing for larger fish. In 1656 in Paris, a Mr. Jaquin extracted from the scales of the common bleak, so-called essence Orientale[1] or "pearl essence",[2] (used in making artificial pearls), which is crystalline guanine.[3]

References
  1. Chisholm, Hugh, ed. (1911). "Bleak" . Encyclopædia Britannica. 4 (11th ed.). Cambridge University Press. p. 55.
  2. Johann Rudolf von Wagner, Ferdinand Fischer, and L. Gautier, Traité de chimie industrielle (Treatise on industrial chemistry), 4th ed., (Paris, France: Masson & Co., 1903), vol. 2, pp. 64–65.
  3. In 1861, French chemist Charles-Louis Barreswil (1817–1870) found that "pearl essence" was guanine. See: Barreswil (1861) "Sur le blanc d'ablette qui sert à la fabrication des perles fausses" (On the white of ablette that's used in making imitation pearls), Comptes rendus, 53 : 246.
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