A planning tool for tropical aquariums.

What this is

A structured database of 135 freshwater species plus a compatibility engine that gives you a verdict on any pair. We check adult size and predation risk, temperament, fin nipping, water requirements and group needs. Every result explains itself. There is no black-box rating.

The same checks drive a tank builder for a whole stocking list, not just two fish at a time, and a browseable fish library with cited sources, minimum tank sizes, and the species we’d steer beginners away from.

How we decide

Conservatively. Where two sources disagree, we take the harder number. Where a pair works for experienced keepers but fails for beginners, we flag caution and explain why. A betta with neons can work, but it isn’t an automatic yes, so we flag caution and explain why.

The full logic is documented in methodology, including a worked example.

What we don’t claim

We have not personally kept all 135 species. We have researched all of them against multiple cited sources. Each fish page shows how confident we are in its numbers, and we don’t hide the low ones.

We also don’t pretend to model your individual filter, your tap water, your work schedule, or the actual temperament of the actual fish in the actual bag. The verdict is a starting point, not a guarantee.

The full list of things we don’t do is on the limitations page.

What you should do

Treat any verdict as the first half of a conversation. Read the reasoning. Check the water parameters against your own tap water: your supplier’s water report or a test kit will tell you, and pH and hardness vary a lot by area. Talk to your local fish shop if it’s a good one, ignore them if it isn’t.

If we’ve got something wrong, tell us at hello@fishori.com. We update profiles and change verdicts when the evidence supports it. We don’t crowdsource verdicts in real time, but we do read every email.

Photos, sources, legal

Species photos come from Wikimedia Commons under free licences (CC BY, CC BY-SA). Each file keeps its original licence and credit; full photo credits here. For data sources see source transparency, and for the legal small print see the disclaimer.