A loose school of bannerfish over the reef

Life in the water

Each fish steers itself.
Each school decides.

Simple rules for every fish, a mind for every school, and a gentle but real food chain.

A dense shoal of silversides turning together

Schools

Three rules, and the beauty emerges

Every fish keeps a little space from its nearest neighbours, swims the way they swim, and stays with the group. On top of that, fish move like real fish: they stay mostly level, bank into turns, beat their tails in time with their speed, and no two are quite alike.

Several schools share the water. They part around each other, and a straggler can be swept along by another school before heading home.

Separation Cohesion Alignment Goal

Dense mixed schools sweeping over the reef

Minds

Each school decides what to do next

Every school has a mood (cruising, alarmed, calm, sleeping or playful) and a mind that plans its next move: explore, rest under cover, regroup after a scare, keep away from a predator, forage, or answer your commands.

Fish get frightened and tired. Tired schools rest, and bored schools go off to ride the currents. Schools take turns resting, each tiring at its own pace, so the water never goes still all at once.

Presence

Reach out, and the fish react. No tutorial needed.

Your head, body, hands and controllers are physical things in the water, and the fish swim around them. Only fast movement frightens them, and the fright spreads through the school as a wave. Hold out a calm, open hand and a few curious fish come over to hover nearby before going home.

Move slowlyThe fish accept you.
Move fastThey scatter.
Open handHold it still to invite the curious.

Golden and silver schools crossing the sunbeams in the grotto

Hunger

Appetite, not need

Fish grow hungry over a few minutes. Feed them, and the nearby fish take turns darting out for the flakes while a hungry school a few metres away notices and comes over. Fed fish lose interest and rest; later they grow hungry again and forage along the currents. The fish never need you.

A coral trout lying in wait on the sand below schools of fusiliers and golden jacks

Predators

A real food chain. Gentle, but not faked.

Fire a hunter from the science gun and it forms out of light. Schools open a clear space around a patrolling bluefin trevally and close behind it. When it grows hungry it darkens and rushes a straggler. Most rushes miss as the fish split around its mouth, but some end in a flurry of silver glints.

The coral trout ambushes from cover, and reef fish dive for shelter when a hunter comes near. A quick hand sends a predator off, and it leaves alone any school you're commanding. Sharks, though, are curious: a blacktip will swim right up for a look at you.

AddThe science gun: Fish, then a hunter.
RemoveIts gear, then the remove button, twice.
How manySix in the room or the hollow, fifteen anywhere else.

The cast

Who lives here

Every species is modelled from reference photographs of the real animal, with its own size, its own way of schooling, and its own place in the food chain.