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Compatibility Report

Can American Flagfish Live With Chili Rasbora?

GuideMyTank compatibility analysis for American Flagfish and Chili Rasbora.

Planning verdict

caution

Conditional

Only plan this pair if every listed condition can be met, and have a separation plan if stress or aggression appears.

Data confidence
high
Assessment source
Structured data model
Data completeness
100%

Blocking risks

No automatic safety blocker was found.

Conditions and cautions

  • One species may be semi-aggressive and require planning.
  • Tank size requirements differ slightly.
  • Water hardness preferences conflict.
  • GH or KH ranges do not overlap well.
  • Breeding aggression can turn an otherwise workable pairing into a caution setup.

Supporting factors

  • Temperature ranges overlap well.
  • pH requirements overlap well.
  • Both species have compatible schooling or group behavior.
  • No predation risk detected.
American Flagfish profileChili Rasbora profileMethodology and limitations

Why This Pair Received Its Verdict

American Flagfish and Chili Rasbora receive a conditional verdict from the current structured assessment. American Flagfish is recorded as semi-aggressive with an aggression level of 4/10; Chili Rasbora is recorded as peaceful with an aggression level of 1/10. The recommendation is based on the combined water, space, behavior, grouping, and predation checks below rather than on species names alone.

  • Temperature ranges overlap well.
  • pH requirements overlap well.
  • One species may be semi-aggressive and require planning.
  • Both species have compatible schooling or group behavior.

Helpful Links

Use the Compatibility CheckerRead the Compatibility Disclaimer

Water Parameter Overlap

American Flagfish has a recorded temperature range of 64–78°F and pH range of 6.5–8. Chili Rasbora is recorded at 73–80°F and pH 4.5–7. Their shared planning window is 73–78°F for temperature and 6.5–7 for pH. A shared aquarium must stay inside the overlap rather than merely touching each species’ outer tolerance.

Aquarium Space and Adult Size

American Flagfish sets the larger listed base aquarium requirement at 20 gallons; the other listed minimum is 5 gallons. American Flagfish is the larger adult by the recorded maximum, reaching 2.5 inches, compared with 0.8 inches. These figures are starting constraints, not a stocking-capacity calculation, because the complete group sizes and bioload still matter.

Behavior and Social Requirements

American Flagfish is a moderate species associated with the mid zone and low flow. Chili Rasbora is moderate, uses the mid zone, and has a moderate flow preference. American Flagfish should be planned as a group of at least 2, while chili rasbora should be planned as a group of at least 8. The aquarium must support both social structures without forcing either species into insufficient space.

Husbandry Fit

American Flagfish is recorded as a omnivore with intermediate care, while Chili Rasbora is a carnivore with intermediate care. Their listed preferred tank styles are community and blackwater. Feeding access, cover, open swimming room, filtration, and observation should be planned around the more demanding requirement rather than averaged between the two species.

What Would Change the Decision?

Use these pair-specific boundaries before treating the verdict as an acceptable stocking plan.

  • Do not proceed unless one stable temperature and pH range can be maintained for both American Flagfish and Chili Rasbora; acclimation does not correct an incompatible long-term range.
  • Treat size, predation, and fin-damage warnings as stop conditions. Extra plants cannot reliably make an unsafe predator-to-prey or fin-target pairing safe.
  • Use broken sight lines and multiple retreats, then separate the pair if either species shows persistent chasing, hiding, clamped fins, or loss of feeding access.
  • Recalculate space using the full adult group sizes—not one specimen of each species—and reject the plan if either species must be understocked socially to fit.
  • Prepare a cycled backup or separation option before introduction; individual behavior can be less predictable than species-level records.

Aquarium Planning Checklist

  • Keep temperature within 73–78°F.
  • Keep pH within 6.5–7.
  • Use at least the larger 20-gallon base requirement before accounting for the complete stocking plan.
  • American Flagfish should be planned as a group of at least 2; chili rasbora should be planned as a group of at least 8.
  • Provide a separation plan and monitor feeding, stress, chasing, damaged fins, and access to preferred habitat zones.

Final Recommendation

Only plan this pair if every listed condition can be met, and have a separation plan if stress or aggression appears.

Sources and Data Provenance

These references support the underlying species records used by this assessment. They do not necessarily evaluate this exact pair together.

  • fishbase.secare · medium confidence
  • fishbase.secare · medium confidence
  • floridamuseum.ufl.educare · medium confidence
  • en.wikipedia.orgtaxonomy · medium confidence
  • en.wikipedia.orgtaxonomy · medium confidence
  • fr.wikipedia.orgtaxonomy · medium confidence
Read the full methodology and limitations
Report quality
supported
Analysis version
2026.09.1
Species data updated
Jul 2, 2026
Review status
Structured automated assessment

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