Duo Aquarium

Build an aquarium with the fish, scenery and water conditions you choose. Explore coral reefs, coastal rockpools, Monterey-inspired kelp forests, seagrass lagoons, reef channels, mangrove creeks, mountain streams and planted freshwater tanks.

Keep Duo Aquarium open on any supported iPhone for an aquarium on your desk or nightstand. Show a clock and local weather, or choose Pure focus to hide all text for an uninterrupted view.

225 RESIDENT CHOICES
Choose from 199 fish varieties and 26 invertebrates, including six freshwater shrimp and snails. Add Peruvian red-spotted green discus in six descriptive colour and pattern options, marbled hatchetfish, elephantnose fish, puffers, whiptails, longhorn cowfish and more. Familiar choices include common and fantail goldfish, tiger oscars, tetras, cichlids, damsels, gobies and wrasses. Each of the 12 starter habitats includes 32–40 residents, with shoals, roaming fish and bottom dwellers suited to the scene. Search for a species or family, add residents individually, or use the habitat's suggested population.

BUILD AND SAVE YOUR OWN TANKS
Add plants, kelp, seaweed, corals, anemones, rocks, wood and shells. Adjust each object's position, depth, size and rotation. Save named aquariums and return to your custom designs. Replace the residents while keeping your scenery, water and lighting, with an option to save a copy first. Your changes are remembered as you move between habitats.

CONTROL THE WATER AND LIGHT
Adjust water clarity, current, brightness and rippling light. Choose daybreak, daylight, moonlight or reef-blue lighting, or follow the time of day. Change how far fish roam and how closely schooling fish stay together. Fish can swim beyond the screen and return, with more space between larger residents. Feed a small batch of food, stop feeding, or pause the tank.

YOUR MUSIC
Choose from six included ambient tracks, play a favourite, or shuffle the collection. You can also connect Apple Music to browse your library, find songs and playlists, and control playback. Apple Music access needs permission; catalog streaming requires an Apple Music subscription. The included tracks work offline without an account. Water sound is separately optional.

CHOOSE WHAT APPEARS
Focus mode hides the clock, weather, app name, habitat label and other overlays. Or choose a clock font, format and position, with an optional date. Add local weather from Apple Weather with System, Celsius or Fahrenheit units, and choose whether to show conditions, daily high/low, rain chance or wind. Weather needs optional location permission and an internet connection to update.

MADE FOR iPhone Duo
Fold part-way to enter Desk view automatically, with the aquarium and clock above the hinge and controls below. Open flat to return to the aquarium. Portrait and landscape layouts also work on other iPhones and iPad. Native fold features require iOS 27.1 or later.

SHARE YOUR AQUARIUM
Send a tank code or link so a friend can visit. Or place two nearby devices side by side and let one tank stretch across both screens. Hosting a visit requires iCloud; nearby sharing uses Wi-Fi or Bluetooth. Your own tank remains saved while you visit another.

Use widgets to see your tank, or feed through Siri and Shortcuts. No ads or tracking. No account is needed for the aquarium or included music.