 The aim of telemetry studies is often to determine the fate and mortality rates of fish. A moving fish is usually regarded as alive and a long-term stationary fish as dead—and the site where it became stationary as the site where it died. Downstream transport of dead fish in rivers can lead investigators to mistake dead fish for live fish. We examined downstream movements of 60 dead Atlantic salmon smolts and 55 dead European silver eels, equipped with radio transmitters and released at hydropower stations in three German rivers.