The Ichthyofauna of Mediterranean Islands: A Review of Sicilian River Systems

Fish fauna in Mediterranean islands has been understudied. The objective of this study is to define the current state of knowledge regarding ichthyofaunal communities inhabiting Sicilian rivers. This review demonstrates that the existing data on the region's fish fauna are fragmented, outdated, and incomplete. However, for the first time, a complete checklist of fish taxa documented in Sicilian rivers is presented, identifying 31 species, of which 19 are autochthonous and 12 are allochthonous. From ecological perspective, excluding sporadic species, only five autochthone species have been found in the inland waters ( Anguilla anguilla, Salmo cettii, Saliaropsis fluviatilis, Aphanius fasciatus, Atherina boyeri ), suffering a strong reduction of their populations along years. A geographical disparity from East to West, with rivers from the first side hosting higher fish biodiversity has been observed. This is probably due to the few information available from West Sicily and the presence of perennial rivers in the East. These knowledge gaps hinder the assessment of environmental degradation and the identification of urgent conservation priorities. A concerted effort to fill them is therefore essential for preserving the island's fish fauna and the health and resilience of its entire riverine ecosystem.