Drag to orbit. Scroll or pinch to zoom. W A S D or arrow keys to travel (Shift for speed, Home to return). H hides or shows these controls. Reflections show best zoomed out, low over the water.
Home size divides the fish's world into square pens with walls; set Wall avoidance to off for open water with no walls. For tighter schools: less personal space, a little more cohesion.
Gulls: wide personal space, weak alignment and cohesion. Starlings: personal space about 1 m, alignment 1.5 over 5 m, cohesion 0.25 over 9 m, restlessness under 1.
This demo needs WebGPU. Open it in a recent Chrome, Edge, or Safari, or in Firefox on Windows or macOS, with hardware acceleration turned on.