Scientific investigations carried out in 2016 in Dniester River (the territorial limits of Republic of Moldova) revealed the following ichtyofaunistic features: 1. In the region of Naslavcea village the specific diversity is the poorest (spring - 5 species, in summer - 7 fish species). The determining factor is the construction of the Novodnestrovsk dam that modified hydrological, thermal and hydrobiological downstream. The only opportunistic species became Gasterosteus aculeatus Linnaeus, 1758, being in both periods of the year the multidominant one (D5) – Dspring = 94,29%, Dsummer =96,75%; euconstant (C4) – Cspring = 80,0%, Csummer=60,0 % and caracteristic (W5) – Wspring = 75,44 %, Wsummer= 58,05 %. 2. In resort near Otaci village we see an increase in species diversity as a result of higher specific thermal gradient value and appearance of numerous patches of aquatic vegetation which comtribute to abundance of small fish species. During the summer time 13 fish species were identified, most of them beloinging to the ecological group of opportunistic species with short life cycle as: Gasterosteus aculeatus Linnaeus, 1758; Leuciscus leuciscus (Linnaeus, 1758); Alburnus alburnus (Linnaeus, 1758); Rhodeus amarus (Bloch, 1782). About medium sized species, systematically is captured: Rutilus rutilus (Linnaeus, 1758); Perca fluviatilis Linnaeus, 1758 and Squalius cephalus (Linnaeus, 1758). Also, since this collection place are systematically captured the Cobitis taxon complex and other guvids species as: Neogobius fluviatilis (Pallas, 1814) and Proterorhinus semilunaris (Heckel, 1837). 3. The control fishering downstream of Soroca city have demonstrated an ichtyofaunistic picture quite surprising for us, significantly increasing both taxonomic diversity (spring - 19 species, in summer - 22 fish species) and abundance of species in captures. The largest share of specis are formed by eurybiont limno-rheophyls fish species such as: Rutilus rutilus (Linnaeus, 1758); Esox lucius Linnaeus, 1758; Carassius gibelio (Bloch, 1782); Rhodeus amarus (Bloch, 1782); Pseudorasbora parva (Temminck & Schlegel, 1846); Cobitis species, Perca fluviatilis Linnaeus, 1758; Alburnus alburnus (Linnaeus, 1758), and other species, which is a strong indicator of biological active process of eutrophication and pollution of this hydrobiotop (where waters nurse of Soroca city are diverse directly in Dniester River). Also, there is still a firm ichtyocenotic structure of indigenous rheophylous fish species as: Barbus barbus (Linnaeus,1758)  (Wsummer = 2,74%), Squalius cephalus (Linnaeus, 1758) (Wsummer = 4,02%) and Leuciscus leuciscus (Linnaeus, 1758) (Wsummer = 6,83%), currently facing negative processes of hydrobiotopic alteration and advance of eurytop fish species. However, these species are part of reproductive litophilous fish species guild that is less affected by sudden alternations level during reproductive unlike phytophilous species group. 4. For Camenca city – Erjovo village section is characteristic the keeping of high values of dominance and constance for species of gobies and Rhodeus amarus (Bloch, 1782), and a significant increasing of ecological indexes for Cobitis complex (Cobitis taenia s. lato) (Wsummer =10,21%) and for Syngnathus abaster Risso, 1827 (Wsummer =11,38%). 5. The scientific fisheries conducted in Goieni Gulf, despite relatively poor specific diversity (spring - 17 species, in summer - 14 fish species), demonstrating the highest quantitative values of Dniester River. Maximum productive contribution in ichtyocenosis structure is brought by eurytope limno – rheophyls small and medium species as: Rutilus rutilus (Linnaeus, 1758) (Wsummer = 34,15%); Scardinius erythrophthalmus (Linnaeus, 1758) (Wsummer = 5,06 %); Perca fluviatilis Linnaeus,1758, (Wsummer = 2,53%); Alburnus alburnus (Linnaeus, 1758) (Wsummer = 3,85%); Rhodeus amarus (Bloch, 1782) (Wsummer = 3,74%). Comparative analysis of catches in the dam of Dubasari reservoirs in different seasons it can be noted the largest differences as a result of hydrobiotop dimensions, offering more opportunities for fish species in space and temporary aspect. 6. Scientific fisheries carried out on the section Criuleni–Vadul-lui-Voda shows a significant increase in species diversity compared to Dubasari reservoir on the account of rheophylous species like Barbus barbus (Linnaeus,1758); Romanogobio kesslerii (Dybowski, 1862); Romanogobio belingi (Slastenenko, 1934); Leuciscus leuciscus (Linnaeus, 1758); Squalius cephalus (Linnaeus, 1758) (spring - 21 species, in summer - 24 fish species). 7. The greatest ichtyofaunistic diversity in Dniester River, within the limits of the Republic of Moldova, is found in the southern terminal point – Palanca village (in spring - 23 species, in summer - 27 fish species), which is a really ecoton zone and fishery comprises fish representatives of various environmental groups. 8. When analyzing ecological similarity index (Sorensen) of fish catches in Dniester River in spring, 2016, using the sapling seine, we find that the greatest degree of similarity of fish communities is observed between the resorts: Soroca - Camenca - 83% (15 common species), Goieni - Dubasari - 81% (13 species common) and Soroca - Criuleni - 80% (16 common species). The lowest value of similarity – 10% is found between the hypothermoficated Naslavcea resort and the intense limnophycated dam of Dubasari (1 common species). Acknowledgment: The study was performed within the national project 15.817.02.27A