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Share of sampled, unoccupied space hidden from the observer.
AQUARIUM FIELD STUDIO / VOL. 02
See what your fish
can’t.
Place a fish. Move a rock. Reveal an invisible world inside your aquarium.
60 × 30 × 36 CMTOP VIEW · GEOMETRIC MODEL
VisibleOccludedRoute
↗ MAKE A MOVEDrag an object, or select it and use the coordinate fields / arrow buttons. Canvas: Tab, then arrow keys.
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At the selected depth; plants attenuate the line.
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Clearance for the route’s circular body model.
Geometry, not a stress score.
01 / ONE-MOVE EXPERIMENT
One move. A different view.
Search nearby hardscape positions. Only propose a change if occlusion increases without reducing passable area or disconnecting the route.
HIDE & SEEK LAB
Route from fish B to the flag. The search prefers darker cells, while keeping a clear corridor. The observer stays fixed.
02 / YOUR SIGHTLINE POSTCARD
Keep the experiment.
Capture a baseline, make a change, and compare the same observer and depth. Export a postcard or share the complete layout.
FIELD NOTES / HOW IT WORKS
Read the water differently.
A small experiment in space, sight and the freedom to be out of view.
Build a scene
Start with the 60 × 30 cm example or enter your own dimensions. Place fish A and B, then add rock, wood or plants. Shapes are simplified footprints, not photographs of real structures.
Reveal the hidden
Choose an observer and one of three depths. The mint field shows direct visibility. Dark cells sit behind opaque structures. Plants dim the field according to your chosen density.
Refine one thing
Move a single structure and compare the result. Check the route and open space as well as the occlusion percentage. A darker tank is not automatically a better tank.
What the numbers mean
We trace a straight line from the observer to each point on an 80 × 40 sampling grid. A rotated ellipse represents rock, wood and plant footprints. Structures only intercept sightlines below their configured height. Fish A and B are evaluated at the same selected depth.
Occlusion = hidden unoccupied samples ÷ all unoccupied samples × 100
A model with clear boundaries
This is a static 2D slice with height filtering, not true 3D vision. Rendering uses 1,440 angular rays for opaque boundaries; reported percentages use the sampling grid. Body clearance is conservative. It omits refraction, turbidity, lighting, species-specific fields of view, water quality and behavior. Plant transmission multiplies across intersected patches; below 50% transmission a sample counts as hidden. Routes use a 40 × 20, four-neighbor grid with body clearance and a visibility penalty. Thin passages may be missed.
TRY THIS / A CHANGE OF SCENE
Three experiments to try
Rock below the surface
Switch between bottom and surface layers. A low rock should stop blocking sightlines when the slice rises above its top.
A screen of plants
Raise plant density or the height multiplier. Compare the same layout and depth; this is a scenario you control, not a biological growth prediction.
The apparent refuge
Add a large obstacle beside a wall. Check whether the explorer can still reach the flag. An occluded pocket and a usable passage are different things.
QUESTIONS / ANSWERS
Aquarium sightline questions
Does a high occlusion percentage mean happier fish?
No. It describes a geometric view from one point and depth. It does not measure stress, welfare, stocking suitability or compatibility. Observe actual fish and seek species-specific husbandry guidance.
Can visual barriers reduce aggression?
Effects vary by species, stocking and shelter availability. Physical structures can interrupt visual contact but can also become contested resources. This tool cannot certify a safe mixed-species tank.
Why does the result change with depth?
Each obstacle has a height measured up from the tank floor. A slice above its top ignores its visual obstruction. The three slices are at 20%, 50% and 80% of water height.
Is this a fish-eye view?
It is a 360-degree point-visibility model, not a retinal or species-specific simulation. Directional fish vision and vision through glass are not modeled.
What does the route percentage show?
The proportion of route segments whose midpoints are hidden from the stationary observer. The shortest visible route may be longer or shorter than a hidden route; we use a visibility-weighted grid search, not a guarantee of fish behavior.
Where is my layout saved?
Only when you press Save, the layout is stored in this browser’s local storage. A shared link encodes the layout in its URL fragment. Anyone with the full link can view it. PNG files download to your device.
RESEARCH / MODEL LIMITATIONS
Evidence, not a welfare score.
Research informs the questions we ask; it does not validate this simulator as a husbandry assessment.
↗ A Comparative Study on Two Territorial Fishes (2021)↗ Key issues concerning environmental enrichment (2009)About this experiment
Created by Hong Dal Oh as an independent educational aquarium planning tool. Model v2.0 · Updated 29 October 2026. Use real measurements and check the final physical layout before moving aquarium decor.
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Use & limitations
This free educational model is provided without a guarantee of accuracy or fitness for animal care. It is not veterinary advice. Do not use the output alone to decide stocking, cohabitation or habitat safety. Exported maps reflect your assumptions.