Bleak - Alburnus Alburnus

The bleak is a very small, silvery and slender freshwater fish that is found across Europe in mainly slow-flowing rivers. It is a member of the carp family, Cyprinidae and is sometimes confused with similar small species such as ruffe, silver bream and young roach.

The body of the bleak is covered in large, shimmering and loose scales that in previous times were taken and used to manufacture artificial pearls.

This fish tends to live and travel in large groups, mainly to safeguard being eaten by larger predators such as pike, kingfishers or herons.

Bleak Identification

The bleak has a slender, streamlined body that is silver in colour with a green - blue steely toned back. Its underside fades to white and its flanks are silver. The body is covered in fairly large scales, with approximately 50 along the lateral line but there are no scales on the fish's head.

The bleak has extremely large eyes in comparison to the rest of its body and its mouth is turned upwards, indicating that it feeds from the surface.

The fins on the bleak's body are grey- white in colour. The concave anal fin is very long and consists of 16-23 branched rays. Both dace and roach have no more than 15 branched rays.

Bleak Habitat

Bleak are found towards the surface of large, slow-flowing rivers. They are found abundantly in England and Wales but are absent from Ireland and Scotland. They are also located in some still waters and can survive in waters with low levels of oxygen. If waters carry roach and dace, it is likely that you will find bleak there too.

Natural Bleak Food

Bleak has a varied diet consisting of insect larvae, molluscs, small crustaceans, animal and vegetable plankton and flying insects that land on the surface of the water. It mainly feeds from the surface, which is why it is often located there.

Bleak Reproduction

Bleak spawn between the months of April and June. The female deposits several thousand eggs on weeds and stones near the edge of the shallow water and the eggs take around a week to hatch. The tiny fry will then begin to feed on microscopic organisms until they are able to manage larger and more nourishing food. Growth is very slow and the bleak will not reach its maximum length for about four years.

Due to large numbers of bleak and their prolific breeding, they often overrun the waters that they inhabit.

The Bleak's Vital Statistics

  • Average weight: ½ oz (15g)
  • Average length: 8 inches (20cm)
  • Specimen weight: anything over 2oz
  • Life-span: 6-8 years
  • Current UK record: 5oz 8 dr, (River Lark, Cambridgeshire)

Rivers with big bleak include:

  • Thames
  • Trent
  • Wye
  • River Monnow, Gwent
  • Great Ouse Relief Channel

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