Native to Washington, Pygmy Whitefish (Prosopium coulterii) are distributed across nine lakes statewide. Seven of these lakes are east of the Cascade Range, including Sullivan Lake. The population status of Pygmy Whitefish in Sullivan Lake is unknown. This study provides background data on the population status of Pygmy Whitefish in Sullivan Lake. Information collected from sixty-seven samples includes species confirmation, age, and condition factor. Species determination was done using DNA barcoding. DNA was extracted using QIAGEN DNeasy Blood and Tissue extraction kits, then sequenced by GENEWIZ Laboratories. We confirmed species identity by uploading sequences to the NCBI BLAST database. Ageing was done using back-calculations of length, length-frequency histograms, and counting the number of annuli on scales and otoliths. Scale samples were taken from beneath the dorsal fin and above the lateral line. Analysis of length-frequency histograms revealed expected age classes between zero and five years. Condition factor (K) displayed strong seasonal variation, with mean K increasing from 0.268 (SD = 0.067) for fish sampled in June to 0.696 (SD = 0.077) for fish sampled in September. Collectively, these results establish a baseline for population status and condition metrics of pygmy Whitefish in Sullivan Lake. This baseline is crucial for informing fisheries management decisions, including the evaluation of potential Bull Trout introductions into Sullivan Lake.