How Fishori works

The pair checker compares two species using structured fields on each profile — not forum anecdotes and not shop tank labels. Verdicts are intentionally conservative, especially where size, temperament, or water ranges diverge.

• Adult size vs shop size. Many fish are sold small but grow fast. Fishori uses realistic adult lengths (and typical aquarium sizes where we track them) when judging space and predation risk — not the size in the shop tank photo.
• Tank volume. Each species has a minimum tank on file. For pairs, the engine considers whether your stated volume (if you enter one) is plausible for both adults together — not “will they fit in a bag.”
• Predation risk. Mouth gap, “may eat small fish” flags, and adult length ratios feed into whether a mix is treated as RISKY or only CAUTION with clear warnings.
• Temperament. Peaceful vs semi-aggressive vs aggressive labels drive how much conflict risk we assume when territories overlap or when flow/activity levels clash.
• Fin nipping. Fin-nipper flags and notes raise the bar for mixing with long-finned or slow species.
• Schooling / group minimums. Shoaling species below their group minimum are stressed first — that stress often shows up as nipping or hiding, which then breaks community mixes.
• Water overlap. Temperature and pH windows must overlap enough to be realistic to keep together; missing overlap is a hard problem, not something we paper over.
• Activity and stress mismatch. Very boisterous fish next to shy, low-flow specialists can be flagged even when water “matches on paper.”
• Territorial behaviour. Where profiles note territory or line-of-sight needs, that feeds cautions — especially for pairs involving cichlids, gouramis, or similar.

Try it directly: Compatibility checker.

The tank builder looks at your whole list at once — not only pairwise checks in isolation. That matters because stocking problems often come from combinations (three “mild” species that all stress each other) rather than a single bad pair.

• Multiple species are evaluated together against tank volume, temperament spread, and repeated risk patterns.
• Issues are grouped so the main blockers surface first instead of burying you in noise.
• When several things are wrong, the engine prioritises primary failures (for example, predation or impossible water overlap) before softer cautions.
• The default stance is beginner-safe: if good references disagree, we bias toward the option that avoids preventable mistakes — especially undersized tanks and risky predation mixes.

• Fish are individuals. Two fish of the same species can behave differently in the same tank.
• Layout matters: rock piles, sight breaks, line of sight, and introduction order change outcomes.
• Published care advice sometimes disagrees. We record confidence honestly and prefer the safer interpretation.
• Shops and social feeds often show juveniles or short-term setups that do not reflect adulthood.

A GOOD verdict means “no red flags on the data we have and the rules we apply” — not a promise that your specific fish will thrive together forever.

Species pages can list linked references and free-text evidence notes. Each profile also carries researchStatus (how far internal review has gone) and sourceConfidence (how tight the numbers feel against what is on file). Those labels are there so you know where a record is strong vs where you should double-check with your own books or club.

More detail on how we think about sources: Source transparency.

• Fishori is not a replacement for an experienced aquarist who knows your water, your room temperature, and your habits.
• It does not simulate real ecosystems — only the fields we model.
• It cannot predict illness, aggression from breeding condition, or a single dominant individual.
• Data grows and changes; a profile may improve over time as we tighten sources.

• Pre-purchase screening: “Is this mix obviously wrong before I pay?”
• Beginner planning: tank size, temperament, and obvious predation traps.
• Avoiding common mistakes: undersized tanks, wrong temperature bands, fin-nipper + long-fin combos.
• Understanding risk: why a mix is CAUTION vs RISKY, in plain language.