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BiologyFreshwater species, found in brooks and rivers. In Slovakia, it occurs in the submountainous zone at altitudes between 465 and 550 m and in Subcarpathian Ukraine it is found almost exclusively above 250 m (Ref. 89241). Adults inhabit piedmont and montane zones in clear, well oxygenated brooks. Ammocoetes live in detritus-rich sands or clay sediments (Ref. 59043). Ammocoetes feed on detritus and insect larvae; this stage lasts for 3.5-4.5 years in Danube drainage (Ref. 59043), or 4 to over 5 months in European freshwater basins (Ref. 89241). Larvae live 4+ - 5+ years (Ref. 89241). Metamorphosis usually starts in July - August and lasts for 1-5 months. Adults feed on the blood and flesh of both living and dead fish. They migrate upstream to the upper reaches of brooks during spawning time in spring (Ref. 12268, 59043). The adult phase lasts 17-19 months, feeding only during the first year. Adults parasitic/scavenger on various fishes. The spawning period varies with location. Fecundity, 7,500-10,300 eggs/female. Dead and spent adults have been found in April and May in Subcarpathian Ukraine, whereas in Romania, spawning is said to take place from the end of May into June in Iara Brook, Transylvania and between the end of June and the beginning of July in Bistra M?rului Brook, Banat. In certain regions of Romania, local people consume (presumably adults of) this species and fishermen also use it (presumably the ammocoetes) as live bait. The feeding phase adults inflict serious damage to trout in Romanian hatcheries (Ref.89241).