Negative impact of increasing fish culture development in Zadar County has been raising concern. The aim of this study is to assess the impact on the physical and chemical parameters of sediment and a water column, while additionally examining the biological impacts on the bethic community. In the period from 2006 to 2013, a total of 18 fish farms and 10 reference stations distanced 500 meters from cages were investigated. Physical and chemical water column analysis reveal significant impact of fish farms in comparison with the reference station for BPK5 and chlorophyll α. Comparison of, TRIX, UNTRIX and an efficiency coefficient of trophic properties, revealed that the proposed TRIX is not adequete enough in demonstrating impact on oligotrophic water nutrient loads. Result of different biological indices reveal a decrease of biodiversity in a near cage vicinity. Cage farm stations with an evident ecological impact were separated trough cluster analysis of pooled data including biodiversity investigation, physical and chemical analysis of water column and sediment. Besides considerable total phoshorus increase in sediment, the stations are characterized with dominance of opportunistic species Antedon mediterranea (Lamarck, 1816); Echinus melo Lamarck, 1816; Holothuria tubulosa (Gmelin, 1791); Belone belone (Linnaeus, 1761); Phymanthus pulcher (Andrès, 1883) and Mytilus galloprovincialis Lamarck, 1819, as well as increased amount of aerobic bacteria, BPK5 and suspended solids.