Abstract
Study attempts to highlight the extent of damage to ihtiocenozelor, given that fish fauna of the river was once very rich in species and abundant quantity. By determination of quality parameters (species composition) of quantitative parameters (numeric stock and gravimetric) and ecological indices (index of ecological values, biodiversity index and IBI) best reflects the degree of dysfunction of the aquatic ecosystem. Maximum abundance of specimens recorded in the mountainous area of Bistrita, upstream Bicaz lake and Poiana Teiului, where influence is greatest. Low values occurring at the confluence with Neagra Şarului. Zoning fishery on the upper Bistrita underwent a number of changes to the existing initial by restricting the grayling zone upstream from Vatra Dornei, restriction area to springs and repleace common nase zone the section Brosteni – Lake Bicaz. Currently dominates the Bistrita River mediterranean barbel zone from Vatra Dornei until the accumulation of Poiana Teiului Integrity of fish communities is good and very good, except for 5 (confluence with Black Şarului Bistrita), being the limit of sustainability.