The Vaki Riverwatcher-PIT integrates a Biomark IS1001 reader and antenna into the Vaki Riverwatcher system. The PIT-tag detection system consists of a shielded antenna that can be mounted to either side of the Riverwatcher tunnel, a low profile submersible IS1001 enclosure, and a 100 ft cable to connect to the Vaki Riverwatcher enclosure. The shielded antenna limits the detection field to the opening of the antenna, preventing the detection of fish that are either in the tunnel or positioned outside of the opening. The PIT-tag detection system can be accessed using Biomark’s Device Manager application on the Vaki Riverwatcher panel computer. Each detection is appended with the date and time of detection to facilitate association with Riverwatcher imaging.