SmartTub vs Koi Feeder
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
SmartTub
Experience a playful virtual bath with floating ducks. Interact with them by tilting your device, shaking to add more, flicking them around, or tapping to hear them quack. Enjoy a simple, interactive entertainment experience.
- Tilt to move ducks
- Shake to add ducks
- Flick ducks
- Tap ducks to quack
- Force Touch on Apple Watch to reset
Read full descriptionHide full description
Replicate the bath by SmartTub and enjoy swinging ducks! How to (iPad) - Tilt Device : move ducks - Shake Device : add ducks - Flick ducks : move ducks - Touch a duck : quack How to (AppleWatch) - Tilt Watch : move ducks - Shake Watch : add ducks - Flick ducks : move ducks - Force Touch : revert to the original number of ducks # To show add-on dialog, please turn "Show add-on" on in the Setting.app. # Demo video : http://www.youtube.com/watch?v=HsD4jtvstL8 Sound Effect ・OtoLogic(https://otologic.jp) ・WEB WAVE LIB(http://www.s-t-t.com/wwl)
Koi Feeder
Interact with digital koi by feeding them. Enjoy a simple, relaxing experience designed to be played with.
- Feed digital koi
- Interact with koi
- Relaxing gameplay
- Simple interface
Read full descriptionHide full description
The application which gives food to koi. Won't you play with koi?
Screenshots
Verdict
The clearest difference is rating: SmartTub at 4.7 against Koi Feeder's 3.0. SmartTub also leads on ads (none vs shown) and update cadence (every 5 months vs every 19 months). Koi Feeder's advantage is in-app purchases (none vs 1) and review sentiment (100% vs 71%). On price and device support there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
Both are free to download. SmartTub sells 1 one-off in-app purchase. Koi Feeder asks for nothing beyond the download.
SmartTub holds the better App Store score, 4.7 against 3.0. That said, the two scores are not equally well evidenced: SmartTub has 13 ratings behind it against 2, so its average is the more settled of the two. Written reviews complicate that: 71% of SmartTub's written reviews are positive against 100% of Koi Feeder's, so the app with the better star average is not the one people write more warmly about.
SmartTub ships an update every 5 months, Koi Feeder every 19 months. The most recent releases landed on November 6, 2026 and November 2, 2026 respectively.
| Parameter | SmartTub | Koi Feeder |
|---|---|---|
| Price | Free | Free |
| Rating | 4.7 (13 ratings) — better | 3.0 (2 ratings) |
| Positive reviews | 70.5% of reviews | 100.0% of reviews — better |
| Number of ratings | 13 — better | 2 |
| Update frequency | Every 5 months — better | Every 19 months |
| Ads | No — better | Yes |
| In-app purchases | Yes | No — better |
| Monetization | Free with in-app purchases | Ad-supported — better |
| Devices | iPhone, iPad, Apple Watch | iPhone, iPad, iPod |
| Requires iOS | 16.6 | 12.0 — better |
| Further details — not scored | ||
| Size | 77 MB | 67 MB |
| Age rating | 4+ | 4+ |
| Developer | sorakaze Inc. | kume toru |
Customer experience
SmartTub
Koi Feeder
Bugs and requests
SmartTub
Reported bugs
3 issues- Widget not working
- App not launching on Apple Watch SE
- App icon not appearing on screen
Requested features
10 requests- Add more toys and variations
- Implement a delete duck feature
- Add different colored ducks
- Allow water to react to touch
- Add a ripple effect
Show 5 moreShow fewer
- Add a one-click clear screen option
- Add more costume options for ducks
- Add different bath themes (e.g., seasonal)
- Add a mode where ducks increase without shaking
- Update widget for iOS 18
Koi Feeder
Not enough reviews yet to summarise bugs or requests.
In-app purchases
SmartTub
- Extension Pack$1.99
Koi Feeder
No in-app purchases
