How we check facts

In short

Our research is gathered by an automated, AI-assisted process: it finds care sources, extracts each fact together with the exact sentence it came from, compares sources and drafts page text. An AI-assisted editorial review, under our editor Marin Hale, checks every value that drives a tank mate verdict against the quoted sources, and resolves every disagreement on those values with a published reason. Other facts that rest on a single source, or where sources still disagree, are marked with † on the page so you can judge them yourself.

Species facts

1. Names and taxonomy come from GBIF and Wikidata, so renamed species (for example the zebra nerite snail, now Vittina natalensis) are matched to their current scientific name.
2. Care facts such as temperature, pH, adult size, lifespan, tank size and group size are collected from three or more independent references. We prefer sources hobbyists trust, such as Seriously Fish, Aquarium Co-op, LiveAquaria, Maidenhead Aquatics and Practical Fishkeeping, and we exclude content farms and general-interest blogs. Every value is stored with the exact sentence it came from, and you can read those quotes under “Where each value comes from” on every species page.
3. Values are compared. When sources agree, we use the consensus. For values that drive tank mate verdicts (temperature, pH, hardness, size, tank and group size, temperament, fins, appetite for shrimp), every disagreement or single-source value goes through editorial review, which picks a value and publishes the reason. Those decisions are listed at the bottom of each species page. Other single-source or disputed values are published with a † marker.
4. Text is checked against the data. Page text is drafted by AI from the reviewed facts only. An automatic check compares every temperature, pH, tank size and length in the text with the data, and rejects drafts that don’t match.
5. Ranges are what fish tolerate, not just the ideal. Some guides give a narrow “ideal” temperature. For tank mate checks we use the range a species is comfortable in, and we say so where it matters.
6. Our own words. Page text is written from the checked facts, not copied from sources. Photos come from Wikimedia Commons under licenses that allow reuse, with credit.
7. Review dates. Each species and verdict page shows when it was last reviewed.

Tank mate verdicts

Every pair of species runs through the same checks. The verdict is the worst result:

• Water temperature. Ranges must overlap with some margin, and coldwater fish aren't paired with tropical ones.
• pH. Ranges should overlap by at least 0.5. A thinner overlap or a gap is a warning: fish adapt to small differences, but one of them will be outside its comfort zone.
• Water hardness. Soft-water fish (like neon tetras) and hard-water fish (like guppies) are flagged, even when the temperature matches.
• Size and appetite. A large fish will eat anything that fits in its mouth. Almost every fish eats baby shrimp, so only the smallest fish get a clean pass with shrimp.
• Fins. Fin-nippers aren't paired with long-finned fish and can harass much smaller, peaceful species.
• Temperament. Aggressive species aren't paired with peaceful ones.

Some behavior can't be computed from facts alone, such as male bettas attacking long-tailed guppies. Those cases have a written note from hobbyist experience, shown under the check it affects.

Tank size matters. Some pairs need more room together than either needs alone, so verdict pages show the answer for each common tank size.

Every tank and every fish is different. Treat verdicts as a starting point, watch new tank mates closely, and have a backup plan.

Corrections

Found something wrong? Email corrections@fishtankatlas.com with the page and what you saw. The sources on each page show exactly where every value came from.