Replication data for: Resource use of Crucian carp along a lake productivity gradient is related to body size, predation risk, and resource competition

We provide stable isotope and gut content data for crucian carp (Carassius carassius) from 12 study lakes located in southeastern Norway. Data were collected between June and August in 2018 and 2019. The stable isotope dataset (SIA) contains nitrogen and carbon stable isotope values of 30 crucian carp for each lake. In addition, we present collected abiotic and biotic data associated with the different lakes. We also provide the total body length, body height, weight, and sex of the different fish species collected in each lake.