Breeding Bleak (Alburnus Alburnus) In The Aquarium

Bleak, Common Bleak, European Bleak, Freshwater Bleak, Silver Bleak, White Fish, Lake Bleak, River Bleak, White Bleak

Distribution

This freshwater species naturally inhabits the open waters of large and medium-sized lakes and slow-flowing rivers, their tributaries, floodplains, and drainage basins to the sea in virtually the whole of Europe and eastern Asia - from France, the UK and Norway through Poland, Romania, Greece to distant Kazakhstan. The fish has also been artificially introduced into Spanish, Portuguese and Italian reservoirs.

External Appearance

The fish is characterised by a elongated, laterally compressed and very streamlined body shape. It has a protruding lower jaw, quite small mouth directed upwards and a broad anal fin. It has no adipose fin. The body color is olive-gray, with a darker back and silvery sheen on the sides. The fins are transparent, the dorsal and tail fins are yellowish-green. During the breeding season, a yellow-orange coloration can be seen on the back and tail of the fish. The male is slightly smaller than the female. The female is more rounded in the belly areas. In the spawning period, the male is covered with spawning rash - colorless, rough skin eruptions, which mainly appear on the top of the head and the back, and on the sides of the fish.

Temperament

This is a social, highly active and shoaling species that forms large congregations, especially in winter and during the breeding season. In an aquarium, we should have a group of a minimum of 8-10 specimens. These fish feed on the water surface (plankton, crustaceans, insects, insect larvae), and therefore mostly inhabit upper water layers. Only at night they descend deeper. During winter, feeding should be reduced. The common roach may nibble on plants and also eats plant residues. It also happens to peck at algae (especially cyanobacteria, green algae, diatoms). The fish is quite jumpy – a tight aquarium cover is necessary. In a large tank (minimum 300 l) the roach can be paired with gudgeon, ladyfish, goatfish, sunfish, vimba, dace or roach.

Aquarium

This species requires a spacious aquarium (longer than it is tall) with open swimming spaces and hideouts among plants (including a small amount of floating plants), roots, rocks and stones. The substrate should be gravel or sandy-gravel with the addition of dried beech or oak leaves, the water flow moderate. A tight aquarium cover is essential, well-oxygenated water, quite strong lighting. The fish is sensitive to poor water conditions - especially oxygen deficiencies. Effective filtration is necessary.

Reproduction

This species is oviparous. Under natural conditions, fish reproduce in a pool (a place on the river where there is a local acceleration of water flow - its damming up), along rocky shores of lakes or among underwater vegetation. The larvae stay close to the river bank or lake, in the littoral zone, whereas the fry move deeper into the reservoir, onto the open waters of the pelagic zone, where they feed on plankton. They reach sexual maturity after 2-3 years and reproduce for 1-2 breeding seasons, in the summer period. In an aquarium, fish reproduce in shallow water, in groups. The female lays eggs in the open water column over a gravelly-stony substrate, between groups of plants with soft leaves, in the morning hours. Water surface agitation is essential. Yellow-amber eggs stick to plants or the substrate. Hatching occurs after about 4-7 days. Parents do not take care of the offspring.