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Built for Duo

Koimono: ASCII Koi Fish Pond

Feed and name koi in a pond drawn with text characters that changes with the seasons.

Individuation Labs LLC · Entertainment · $0.99

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iPhone screenshots

Koimono: ASCII Koi Fish Pond — iPhone screenshots 1
Koimono: ASCII Koi Fish Pond — iPhone screenshots 2

How it uses iPhone Duo

A narrow stream runs down the outer display. Unfold the Duo and the same scene widens into a koi pond.

What’s New

Version 1.0.2 ·

The card behind the ? sign now has Share and Rate buttons, and a link to Chiptune, the app the pond's song was written in. While your iPhone is charging, the screen stays on and the signs fade away after 20 seconds, so the pond can run as a screensaver on your desk or nightstand. Touch the screen to bring them back.

App Store descriptionWritten by the developer.

I love ASCII animation, and I wanted to make something fun and calming for the iPhone Duo and every other iPhone. Koimono is a koi pond drawn entirely in text characters, and it moves far more smoothly than letters and symbols have any right to. The whole pond is redrawn up to 120 times a second on ProMotion displays. The koi bend and glide as they swim, ripples spread out wherever you touch the water, and the light on the surface changes through the day. I wanted it to show how beautiful plain ASCII can be. Nine koi live in your pond, each with its own name. Rest a finger in the water and they come to see what it is. Hold one to see its name and age, and rename it any time. Feed them a handful, call them over, or scatter them. A new koi arrives every five days until there are twelve. Then you can free one to make room for the next. The pond mirrors the time of day, the phase of the moon and the seasons: blossom in spring, extra lily pads in summer, falling leaves in autumn and snow in winter. Rain comes and goes, and now and then a visitor stops by: a frog, a dragonfly, a turtle, a heron or a cat. A quiet pond song plays under it all, and the music sign turns it off. Plug your iPhone in and the screen stays on, and the signs fade away until you touch it, so the pond works as a screensaver. ON THE IPHONE DUO When the iPhone Duo is closed, Koimono is a calm stream running down the outer screen. Open it up and the stream widens into a whole koi pond. A HOME SCREEN WIDGET Small and medium widgets show your own koi, the sky for the hour and tonight's moon. ONE PURCHASE, NO ADS, NO TRACKING You pay once. There are no in-app purchases, no account and no ads. Koimono doesn't collect any data and works offline.

Koimono: ASCII Koi Fish Pond on iPhone Duo: FAQ

Is Koimono: ASCII Koi Fish Pond optimized for iPhone Duo?

Yes. Koimono: ASCII Koi Fish Pond is Built for Duo: it uses the fold, Split View or the outer display. Verified on November 15, 2026 (Developer statement).

What does Koimono: ASCII Koi Fish Pond look like on iPhone Duo?

A narrow stream runs down the outer display. Unfold the Duo and the same scene widens into a koi pond.

How much does Koimono: ASCII Koi Fish Pond cost?

Koimono: ASCII Koi Fish Pond costs $0.99 on the App Store.

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