Bleak have an elongated, flat body with a long anal fin and have pointed heads with a relatively small upturned mouth. They are shiny silvery in colour and have a dark green/black back and fins that are pointed and colourless. Their maximum length is approximately 20cm.
Bleak’s paper-thin scales dislodge very easily when handled and in 17th Century Paris, their scales had a so- called ‘pearl essence’ abstracted from them. In 1844 the same compound, then named ‘Guanine’, was first extracted from seabird droppings: hence the use of the word ‘guano’ to refer to their odorous droppings, which contains high levels of uric acid: from which Guanine can be artificially manufactured.
Crystalline guanine is currently used as an additive to various products to give a ‘pearl essence’ for an iridescent effect, and is also used in metallic paints, simulated pearls, eye shadows and nail polish.
It forms large shoals in rivers with a medium flow, very active and living close to the surface, they feed on small insects on or are near to the surface: sometimes jumping clear when chasing them. They also feed on small insect larvae, aquatic worms and plant detritus. Bleak prefer open water and favours areas where there is an inflow of food from river junctions, weirs and pumping stations.
Bleak generally spawn in April to June in shallow waters of at least 15°C, with females producing some 5,000 eggs/ounce of bodyweight, which are sticky and fall through the water column and adhere to aquatic plants and gravel. Fry grow quickly and attain 50% of adult size within a year and reach sexual maturity within 1-3 years, rarely living more than 6-years.
They occasionally spawn with Chub, resulting in a very similar fish, which unfortunately attain the size of the Chub, otherwise it could provide great sport since Bleak are a designed for speed and combined with a Chub’s strength, a 2lb fish would have been a lot of fun to fish for – maybe one day !
Since Bleak are surface feeders and will be seen swirling and dimpling the surface, try float fishing at a depth of just 1-3 feet with very small baits such bread-punch or single maggot with loose-feed little and often: bites will be quick and usually on the drop as the bait falls through the water.
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