Free app · no sign-up · no ads
Your aquarium, without guesswork.
Enter your tank’s litres and your tap water: Ondaqua tells you which fish and plants do well, how many to keep and what not to buy. Then a log for water tests and water changes.
The beginner’s guide, free
The steps to start without losing fish: water, the cycle, what to buy and what not to. We are finishing it: leave your email and you get it as soon as it is ready.

What the app does
Your tap water
Tap water is often hard. Ondaqua tells you which species cope with it and which suffer.
Fish that get along
Adult size, temperament and temperature: the warnings come before you buy, not after.
Your aquarium log
Tests, water changes and reminders. The log stays on your phone.
Ask the expert
One specific question, one short answer using your tank’s data. Answers are AI-generated.
Who is behind it
I’m Fabiano. I keep aquariums at home in Castellón, Spain, with the hard water we have here. Ondaqua comes from a simple question: what can I put in my tank without anyone suffering? The app is free and ad-free; if you buy something through its links, the shop may pay us a small commission at no cost to you.
— Fabiano from Ondaqua