FishTracker is a student-oriented citizen science project that records and maps the presence of about a dozen species of fish, both endangered and invasive, in New York State. Students collect water from lakes and rivers across New York. They pump water samples through glass fiber filters which then are placed in buffer to prevent degradation of environmental DNA (eDNA). The filters are returned to the lab at Cornell and each filter is carefully treated to isolate any eDNA present. This video shows the step-by-step process used to isolate the eDNA, starting with the field sample received from the students and ending with the extracted DNA used for quantitative PCR (qPCR).