Impacts specific to tench are difficult to find, as this species is often lumped together with others in the Cyprinidae family, such as koi and common carp. In Australia it is thought that tench may directly compete with trout and native fish for food resources (IFS, 2000). The ability of tench to survive in degraded environments causes some confusion, as it is unclear whether they contribute to this degradation or simply inhabit a niche that native fish cannot occupy. Most impacts are likely to be related to the wide range of organisms consumed by tench. An experimental study by Bekliogu & Moss (1998) showed that tench can increase periphyton (algal) biomass through selective predation on gastropods, which keep periphyton under control through grazing. This 'trickle-down' effect could have negative impacts on aquatic communities if it occurs to a significant extent in the wild. Impacts of tench were reviewed by Rowe (2004). There is no evidence that they affect other fish directly, however, a number of studies have implicated them in water quality decline.
No Impact information recorded for Tinca tinca