Aquarium Screensaver_
Who lives in this scene
Eight scenes
Keyboard & mouse
Guide — a living fish tank on any screen
Choose Tropical reef, Glass tank, Deep sea, Jellyfish night, Koi pond, Kelp forest, Sunset lagoon or Sunken arch. Keys 1 to 8 switch at once.
Click or tap the water to drop food and watch the fish race for it. Long-press, Shift-click or press G to tap the glass and startle the school.
Set the number of fish, speed, size, light and bubbles, switch species on or off, and pick day, dusk, night or Auto to follow your local time.
Press Enter fullscreen, double-click the water or press F. The display is kept awake where the browser allows it. Move the mouse to bring back the controls.
Switch on the generated bubbling water sound, show a clock (T), save a PNG (P) or copy a link that reopens your exact tank.
What each scene offers
- Tropical reef
- Branching coral, sea fans, a damsel school, a turtle and a seahorse
- Sunset lagoon
- Amber shafts over pale sand, rays and turtles
- Sunken arch
- Weathered pillars and an arch overgrown with coral
- Kelp forest
- Tall swaying kelp, golden light and silver sprats
- Glass tank
- Gravel, driftwood, plants, an air stone and reflections on the pane
- Koi pond
- Top-down view with lily pads, water lilies, ripples and floating food
- Deep sea
- Marine snow, glowing vents, lanternfish and a lure-waving angler
- Jellyfish night
- Pulsing bells with trailing tentacles; plankton sparkles under the pointer
- 1 to 8
- Switch scene
- F / Space
- Fullscreen / pause
- E / G
- Drop food / tap the glass
- D
- Cycle day, dusk, night, auto
- T / P / S
- Clock / save PNG / water sound
- R
- Reset the scene to its defaults
A free aquarium screensaver and virtual fish tank, explained
What is this aquarium screensaver?
It is a virtual fish tank that runs in your browser and turns any screen into a calm, moving picture. There are eight scenes: a coral reef, a planted glass tank, the deep sea, a jellyfish night, a koi pond seen from above, a kelp forest, a sunset lagoon and a sunken arch. Everything is drawn live on an HTML5 canvas, in your own browser, with no video files and no download.
The fish are original designs drawn in code: inspired by real reef, freshwater and deep-sea animals, but not copies of real species or of any cartoon character. Each one has its own body shape, markings and way of moving: some dart and glide, some hover, some forage along the bottom, some travel in schools.
Use it as a screensaver on a monitor or TV
Open the page, choose a scene and press Enter fullscreen (or F, or double-click the water). The controls fade away after a couple of seconds and so does the mouse cursor. In fullscreen the page asks the browser to keep the display awake, using the Screen Wake Lock feature where it is available. Where a browser does not offer fullscreen to web pages, as on iPhone, the page fills the browser window instead. A web page cannot register itself as your operating system’s screensaver, so to run it on a TV open it in the TV’s browser or cast it from a laptop, and set your computer’s sleep timer to never if you want it on all day.
Eight scenes, eight moods
The reef and lagoon are bright and sunlit, with light shafts and moving caustics on the sand. The glass tank shows a tank from the outside, with a lid light, a frame and soft reflections on the pane. The deep sea and jellyfish night are dark and glowing. The kelp forest sways in a slow surge, and the sunken arch is a quiet ruin full of reef fish. In the koi pond you look straight down at koi, which are ornamental carp bred in more than a hundred colour varieties, swimming under lily pads, with ripples where they sip food from the surface.
How the fish move
Schooling fish follow the three steering rules described by Craig Reynolds in his 1987 SIGGRAPH paper on simulated flocks, herds and schools: avoid collisions with neighbours, match their velocity, and stay close to them. On top of that every species has its own gait. Wrasse-like fish alternate bursts and glides, seahorses hover near a favourite spot, corydoras-like fish forage on the gravel, turtles and rays glide, and jellyfish pulse their bells and drift on the thrust. Each fish bends along its body in a travelling wave that gets faster when it swims faster. Deep fish are drawn a little hazier than near ones, which gives the tank depth.
Feeding the fish and tapping the glass
Click or tap the water to drop a pinch of food. Hungry fish turn towards the closest flake, race each other for it and eat it; flakes nobody catches settle on the floor and disappear after a while. In the koi pond the flakes float on the surface and the koi sip them with a small ring. Tapping the glass (Shift-click, long-press or G) sends a shock ring across the pane: schools scatter, jellyfish pulse harder and the little round puffer inflates. Moving the pointer through the dark scenes makes tiny plankton flash.
Light shafts, caustics and the time of day
Sunlight reaches the water as slowly swaying shafts. The bright, shifting web on the sand is called a caustic: the rippling surface bends the light like thousands of small lenses and focuses it into moving lines. Here it is a tile of that pattern, scrolled in two layers at different speeds. The Time of day setting offers Day, Dusk, Night and Auto. Auto follows the clock on your device: day from about 8:30 to 16:30, dusk fading in on either side, night from about 20:30 to 5:30. Glowing creatures shine brighter as it gets darker, and the stone lanterns beside the koi pond light up in the evening. The Light slider works like an exposure control for the whole scene.
The deep sea: marine snow and living light
In the deep-sea scene the drifting white specks are marine snow, the name oceanographers use for a shower of organic material falling from the upper waters to the deep ocean. NOAA describes it as dead plants and animals plus fecal matter, sand, soot and other dust. The lanternfish, comb jellies and angler with a glowing lure are original creatures inspired by the dark water, not portraits of real species.
Why watching fish is relaxing
Slow, unpredictable movement in blue-green light holds attention without demanding it. A study by the National Marine Aquarium in Plymouth with the universities of Plymouth and Exeter, published in 2015, found that watching an aquarium lowered heart rate and blood pressure, and that people looked longer and felt better when there were more fish in the tank. A screen is not a real tank, but it gives a similar calm background for a desk, a reception or a waiting room, without the cleaning.
Performance, quality and battery
The page uses time-based animation, so fish swim at the same speed on a 60 Hz and a 144 Hz display. The static scenery is drawn in small slices before it appears, so the page never freezes while a scene loads. If your device runs below about 38 frames per second for a few seconds, Auto quality lowers the number of particles and details; you can switch that off in Options or add aq=0 to the link. The canvas follows your display’s pixel density up to 2×, with a size cap, which keeps it sharp without wasting power. When the tab is hidden the animation stops completely. For long runs on a laptop, keep it plugged in.
Tips
- Lower Light and choose Night for a dim bedroom or a quiet corner of a room.
- Turn Clock on for a screen that is also useful across the room.
- Use the species buttons to keep only the fish you like; the rest of the school fills in.
- Copy link reopens the exact scene, sliders and time of day. Add
fs=1to open straight into fullscreen. - Save PNG saves the current frame, handy as a wallpaper.
- If your device asks for reduced motion, the page opens in the slow Glass tank scene the first time you visit.
Privacy
The tank runs entirely in your browser and nothing you do in it is uploaded: no accounts, no uploads and no sound files. The optional water sound is generated by your browser’s audio engine, is off until you switch it on, and needs no download. Your last settings are stored only on your own device, in your browser’s local storage. Like the rest of this site, the page loads its font from Google Fonts and uses cookie-free, privacy-first analytics to count page views.