Watch the sonar video from the beginning, making sure that all fish are detected with a bounding box and tracked throughout their movements in the field of view.
If a track ends before the fish is done moving, you can easily continue the track by turning on the interpolation on the last frame that the fish was detected. This allows you to move the box with the fish throughout the rest of the video and ensure the accuracy of counts.
For fish that are not detected by the AI, add your own bounding box, turn on interpolation, and follow the fish until it has passed through the sonar field of view, or until the video ends. This will ensure that the counts produced in the web app are accurate.