Examination of rare earth element concentration patterns in freshwater fish tissues

•We surveyed rare earth element concentrations in different tissues of 10 freshwater fish species.•Concentration patterns are summarized for different fish tissues.•We examined concentration patterns for different ages and sizes of fish.•Evaluated bioaccumulation potential of lanthanides in different species and tissues of fish.•Report a large data set for fish that adds to limited information in the published literature. Rare earth elements (REEs or lanthanides) were measured in ten freshwater fish species from a reservoir in Washington State (United States). The REE distribution patterns were examined within fillet and whole body tissues for three size classes. Total concentrations (ΣREE) ranged from 0.014 to 3.0mgkg−1 (dry weight) and averaged 0.243mgkg−1 (dry weight). Tissue concentration patterns indicated that REEs accumulated to a greater extent in organs, viscera, and bone compared to muscle (fillet) tissues. Benthic feeding species (exposed to sediments) exhibited greater concentrations of REEs than pelagic omnivorous or piscivorous fish species. Decreasing REE concentrations were found with increasing age, total length or weight for largescale and longnose suckers, smallmouth bass, and walleye. Concentration patterns in this system were consistent with natural conditions without anthropogenic sources of REEs. These data provide additional reference information with regard to the fate and transport of REEs in freshwater fish tissues in a large aquatic system.