The construction of a dam on a river can block or delay fish migration and thus contribute to the decline and even the extinction of species that depend on longitudinal movements along the stream continuum during certain phase of their life cycle. A non-exhaustive review of the current status of the use of fish facilities at dams throughout the world is presented. Upstream passage technologies can be considered well-developed only for a few anadromous species including salmonids and clupeids in Nord America and Europe. These is an urgent need for better biological information and to do fish passage research for other native species. In addition to problems relating to fish passage at obstacles, there are indirect effects of dams which may prove of major significance such as changes in flow, water quality, the increase in predation and drastic changes to the habitat upstream or downstream.