Cone cross-section
Drag the fish through the cone. The right panel shows what the sonar would draw.
Resulting sonar trace
Fish near the cone center make tall, full arches. Fish at the edge enter and exit late — they make shorter, thinner half-arches or dots.
Full arch
Fish swam straight through cone center.
Half arch
Fish grazed the cone edge.
Dot / dash
Fish barely entered the cone, or stationary.