FishTank Diary is an offline aquarium logbook for iPhone and iPad, made by an aquarist who kept losing track of which tank got which water change. It logs water tests, maintenance and feeding, keeps a dated history per tank, and reminds you what is due next. It is deliberately small: no account, no cloud, no subscription, no social feed.
Why no account
An account means a server, a password, a privacy policy with teeth and a support burden that eventually becomes a subscription. None of that makes a nitrate reading more accurate. Removing it removes the recurring cost, and it removes the failure mode where your log disappears because a service shut down.
The trade-off is honest: no account also means no sync between devices in the current release. CSV export exists so the data is never trapped.
Why the app is opinionated about small tanks
Most aquarium apps are built around big community tanks and saltwater reefs. The faster-growing part of the hobby is nano and small planted tanks, where the water volume is tiny and the maintenance rhythm is the whole game. A record of “I changed 30% three days ago” is worth more there than a parameter library.
What the app is not
- Not a diagnostic tool. It flags readings outside the range you set; it does not identify disease.
- Not veterinary advice. For a sick animal, talk to a vet.
- Not a social network, a shop, or a dosing calculator.
The free version covers a single tank with unlimited logging, forever. Pro is $3.99 once — unlimited tanks, trend charts and CSV export. No subscription, no ads, no data collection.
Contact
Bug reports, feature requests and corrections to anything published here: support@fishtankdiary.com. Corrections to the guides are especially welcome — fish keeping advice ages badly.
