The European Fish Index (EFI), the Fish Index Austria (FIA) and the German fish-based assessment system (FiBS) were tested using Slovenian fish data. Fish were sampled using electric fishing procedure in small and medium sized rivers of the Danube river basin in the Ecoregion Alps. To test the appropriateness of selected indices, correlations between hydromorphological alteration pressure and fish indices were calculated. Hydromorphological alteration pressure was defined using seven Slovenian hydromorphological quality classes. Correlations were positive and statistically significant in all cases but the coefficient of determination (R2) was very low, not exceeding 0.15. The highest R2 was calculated using FIA without the biomass knockout criterion. Possible reasons for the low R2 values including criteria for the hydromorphological alteration classes, fishery management influence and tested fish indices, are discussed. In addition, appropriateness of the inclusion of allochthonous fish species in the fish-based assessment systems is discussed.S slovenskimi podatki smo testirali Evropski ribji indeks (EFI), Ribji index Avstrija (FIA) in Nemški sistem vrednotenja na podlagi rib (FIBS). Ribe smo vzorčili z elektriko v malih in srednje velikih rekah donavskega porečja ekoregije Alpe. Za preverjanje primernosti izbranih indeksov smo izračunali soodvisnost med razredi hidromorfološke spremenjenosti rek in ribjimi indeksi.Pozitivno in statistično značilno soodvisnost smo ugotovili v vseh primerih, vendar je bil koeficient determinacije (R2) nizek in v nobenem primeru ni presegal 0,15. Najvišji R2 je bil izračunan, ko smo uporabili FIA brez izključitvenega sokriterija. Razpravljamo o možnih vzrokih za nizke vrednosti R2, vključno s kriteriji za razrede hidromorfološke spremenjenosti rek, ribiškim upravljanjem in testiranimi indeksi ter o primernosti upoštevanja tujerodnih vrst v sistemih vrednotenja ekološkega stanja
