Click / drag → draw
Right-click → erase
Space: play/pause
S: step C: clear
R: random fill
The Phantom Fish Tank
A web port of Brian Silverman's 1987 cellular automata laboratory
This is a microworld for exploring emergence. You set up a starting pattern and choose a set of rules; then the computer runs the rules generation by generation. Surprising structures — gliders, blinkers, oscillators, even logic gates — can emerge from very simple rules.
The Basics
Pick an automaton from the Automaton dropdown.
Draw a pattern on the grid by clicking and dragging. Right-click (or use the Clear button) to erase.
Press Play to watch the pattern evolve. Use Step to advance one generation at a time.
Adjust the speed with the slider (1–60 generations per second).
Drawing Cells
For multi-state automata (Logic World, Wire Rules, Mutants), use the Draw State picker to choose which kind of cell you're painting.
The grid wraps around at every edge — left meets right, top meets bottom (a torus).
Try a preset pattern from the Preset dropdown, then hit Load Pattern.
The Built-in Automata
Name
What it does
Conway's Life
The classic. Birth on 3 neighbors; survive on 2 or 3. Produces gliders, blinkers, glider guns.
Fredkin's Game
A cell lives if it had an odd number of live neighbors. Every pattern self-replicates.
Color Life
Conway's rules with aging cells. Survivors cycle through a rainbow before fading to white.
Logic World
Four cell types (background, glider, brick, catalyst) that let you build computer logic gates.
Wire Rules
Electrons (head + tail) propagate along wires. You can build diodes, gates, even adders.
Mutants
Three states (dead, ghost, live). A wild self-organizing world where many shapes act as gliders.
Creating Your Own Rules
Select ✎ Custom Rule… from the Automaton dropdown to open the rule editor.
The custom editor uses B/S notation, the standard for two-state cellular automata:
B (Birth): tick the boxes for the neighbor counts that make a dead cell come alive.
S (Survive): tick the boxes for the neighbor counts that let a live cell stay alive.
Any unchecked count means the cell dies (or stays dead).
Conway's Life, for example, is B3/S23: a dead cell with exactly 3 live neighbors becomes alive; a live cell with 2 or 3 neighbors survives; everything else dies.
Try this: Pick the “Named rules” dropdown for a guided tour — HighLife, Maze, Seeds, Day & Night, Diamoeba and more. Each behaves wildly differently from Conway's Life.
Designing a Rule From Scratch
Open the rule editor (Custom Rule).
Start with a simple guess — e.g. B3/S23 — and click Random Fill.
Press Play and watch the behavior. Most rules either die out instantly, fill the grid with chaos, or freeze. Interesting rules sit on the edge.
Toggle one checkbox at a time. Tiny changes in B/S can completely transform the world.
Try patterns: a single cell, a line, a small cluster, a glider from a known rule.
Heuristics for finding interesting rules:
Rules with a small number of birth conditions (e.g. just B3, or B36) tend to be the most lively.
If nothing survives, your S set is too restrictive.
If everything spreads forever, your B set is too generous.
Rules where B and S overlap heavily (like B3/S23) often produce the richest emergent structure.
Fish Tank Mode
Click 🌀 Fish Tank Mode to let the program run itself: it picks a random rule, fills the grid with random cells, and lets it evolve, switching to a new rule every 10–25 seconds. Brian Silverman called the original software “The Phantom Fish Tank” because he once left it running in his living room for a year as an electronic aquarium.
Keyboard Shortcuts
Space — Play / Pause
S — Step one generation
C — Clear grid
R — Random fill
Things to Try
Load Conway's Glider Gun preset and watch it shoot gliders forever.
Load R-Pentomino in Conway's Life. This 5-cell shape evolves for 1103 generations before stabilizing.
In Fredkin's Game, draw any shape, run it — you'll see eight copies appear, then sixteen, and so on.
In Wire Rules, load the Electron Loop and watch the electron circulate forever.
In Mutants, click Random Fill and just watch. Gliders of many sizes will emerge, collide, and mutate.
In Custom Rule, try B2/S (Seeds) — an explosive world where nothing survives.
Based on The Phantom Fish Tank: An Ecology of Mind by Brian Silverman (LCSI, 1987)