Bleak

Names in dialect: aola, pessata, zentilot, pes zentil, torbolana, aoletta.

The bleak is a slender fish with an almost straight, greenish brown back and metallic reflections. It has a long dark band running along the flanks (not always evident) and a shiny silver belly. The head is small with large eyes and an upturned mouth; its fins are pointed. It usually reaches 8 – 10 cm in length.
The bleak’s favourite habitat is valley bottom lakes and slow running waters. It tends to remain near the surface where it finds more plankton to feed on. It is highly gregarious and in large lakes can form enormous schools, which can reach several hundreds of kilos in weight. It represents the main food source for predatory fish (trout, European perch), which attack the schools forcing the bleak to leap out of the water in flight.
It spawns from May to August, when the water temperature exceeds 16°C; each female deposits about a thousand eggs on one night in shallow waters in gravel near the shore. The fry hatch about ten days later. It has been known to form hybrids with chub.
Bleak were an important part of the diet for people living along lakeshores and were eaten both fresh and preserved in salt; also people living far from the lakes were familiar with them. Up until the 1940s travelling fishmongers would cycle up the valleys in Trentino with a crate of bleak on their bikes, which they sold in the squares of the villages along the route.
Bleak is an important species for commercial fishing, and on Lake Garda used to account for 30 – 35 % of total fish caught (1300 – 150 tonnes/year with fluctuations due to hauls of lake shad, a plankton-eating species with which it competes for food). During the spawning period peasants often used to spend their nights fishing from the lakeshores.
There has been a significant reduction in the numbers of bleak populations. Spawning areas are often disturbed by bathers or jeopardised by artificially raising or lowering water levels in lakes used to produce hydroelectricity or for irrigation. Fishermen sometimes place a few cubic metres of gravel near the shoreline, in areas not used by bathers to improve spawning areas.