ReefKeeper vs FishDiary
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
ReefKeeper
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ReefKeeper helps aquarium hobbyists and maintenance professionals keep tanks healthy through fast water parameter tracking, maintenance reminders, and visual trend analysis. Whether you manage a freshwater aquarium, reef tank, or saltwater system, ReefKeeper keeps your data organized and accessible. First‑Week Livestock Watch gives every new livestock introduction its own seven-day record. Log daily observations and equipment checks, follow guided core water checks, and keep results in your normal aquarium history. If something looks concerning, ReefKeeper provides measured next steps, not a diagnosis or treatment plan. FEATURES • Track water parameters • Log pH, salinity, nitrate, phosphate, alkalinity, calcium, magnesium, temperature, and more • View historical trends with interactive charts • Create recurring maintenance schedules • Track water changes and equipment maintenance • Manage multiple aquariums • Offline-first architecture • Export aquarium data PRO FEATURES • Unlimited aquariums • Advanced graphing • Custom safe ranges • Dosing calculators • Data export • Professional maintenance tools Designed by aquarium enthusiasts who wanted a faster and cleaner alternative to paper notebooks and complicated enterprise software. Privacy Policy: https://beartrailworks.com/privacy Terms of Use (EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/
FishDiary
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FishDiary is a quiet log book for aquarium keepers. Write down what you did to each tank and the water values you measured, then look back at how things changed. FishDiary keeps records. It does not decide anything for you: no scores, no verdicts, no advice. What you write is what you get back. WATER VALUES, DRAWN AS A LINE Save pH, GH, KH, NO3, NO2, NH3, PO4, Ca, Mg, temperature and salinity, each with the unit you actually use. Every tank gets its own chart, so a slow drift over several weeks is easy to notice. If a value you follow is not on the list, add your own. TODAY'S RECORD IN A FEW TAPS Log water changes, feeding, algae removal, dosing, equipment care, water tests and anything else. Add a date, a note and photos. You can define your own work types, and record the same work for several tanks at once. RECORDS AND PLANS ON ONE CALENDAR What you have done and what is coming up sit on the same calendar. Set repeating plans for weekly or monthly work. If you want a nudge, switch on a daily summary or a water change notification and pick the time yourself. YOUR TANKS, YOUR WAY Add as many tanks as you like, freshwater or marine, with photos, tags and the details you care about. Search across every tank and record when you need to find something. Archive a tank when it is closed down, and bring it back whenever you want. FREE AND PRO The whole app is usable for free, with a small banner at the bottom of three screens. On the free plan you can create up to three custom water parameters, custom work types, repeating plans and tags, and attach up to three photos per entry. Pro removes the banner and those limits, and adds export: - CSV of your tank list, care history, care summary or water values - PDF report for a single tank, or for your whole collection Pro comes as a monthly or yearly plan, or as a one-time Lifetime purchase with no renewal. A FEW MORE THINGS - Your records stay on your device. No account, no sign-in. - Backup and restore, so moving to a new phone keeps your history. - Light and dark appearance, or follow your system setting. - Available in 19 languages. Terms of Use: https://fishdiary.doooooraku.workers.dev/terms/ Privacy Policy: https://fishdiary.doooooraku.workers.dev/privacy/
Screenshots
Verdict
The clearest difference is ads: ReefKeeper at none against FishDiary's shown. ReefKeeper also leads on update cadence (weekly vs monthly). On price, in-app purchases, device support and iOS requirement 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. ReefKeeper sells 3 in-app purchases, starting at $4.99 per month and FishDiary sells 3 in-app purchases, starting at $1.99 per month. Whichever you choose, the download price is not the number that matters.
ReefKeeper ships an update weekly, FishDiary monthly. The most recent releases landed on October 31, 2026 and October 25, 2026 respectively.
| Parameter | ReefKeeper | FishDiary |
|---|---|---|
| Price | Free | Free |
| Update frequency | Weekly — better | Monthly |
| Ads | No — better | Yes |
| In-app purchases | Yes | Yes |
| Devices | iPhone, iPad | iPhone, iPad |
| Requires iOS | 17.0 | 16.4 — better |
| Further details — not scored | ||
| Size | 5 MB | 115 MB |
| Age rating | 4+ | +4 |
| Developer | Jose Salcido | MAKOTO NAKAGAWA |
In-app purchases
ReefKeeper
- Reef Keeper Pro Monthly$4.991 Month
- Reef Keeper Pro Yearly$44.991 Year
- Reef Keeper Pro: Lifetime$99.99
FishDiary
- FishDiary Pro Monthly$1.991 Month
- FishDiary Pro Annual$9.991 Year
- FishDiary Pro Lifetime$19.99








