The embryonic state of our knowledge regarding the simultaneous uptake of trace metals via multiple routes in aquatic organisms makes it difficult to accurately assess the bioaccumulation and risk of metals. This study used cadmium (Cd) and a demersal marine fish (the yellowstripe goby) as a model system to determine tissue-specific uptake of Cd under conditions of simultaneous exposure to Cd from water, sediment and diet. A triple stable isotope tracing method was used in which each exposure route was spiked by a different stable isotope (Cd-110, Cd-111 and Cd-113). The results revealed that the fish took up waterborne and sedimentary Cd via gills and gastrointestinal tract (GT), and that of dietary Cd was via the GT. The gills absorbed Cd predominantly from water (77.2-89.4%) whilst the GT absorbed Cd mainly from diet (81.3-98.7%). In the muscle and carcass, the Cd uptake was mainly from the diet (47.1-80.4%) and water (22.8-51.6%). Our study demonstrated that when aquatic animals were subject to simultaneous exposure through multiple uptake routes, the uptake and relative importance of each route for metal accumulation was highly tissue-specific and more complex than a single route of metal exposure.