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Compatibility Report

Can American Flagfish Live With Green Severum?

GuideMyTank compatibility analysis for American Flagfish and Green Severum.

Planning verdict

incompatible

Not recommended

Do not plan a shared aquarium for this pair. Choose a different tank mate or maintain separate aquariums.

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

Blocking risks

  • Size and diet create a predation risk.

Conditions and cautions

  • Both species may show territorial behavior.
  • One species should be maintained in a proper school or group.
  • One species requires a significantly larger aquarium.
  • Water hardness preferences conflict.
  • GH or KH ranges do not overlap well.
  • Two non-peaceful species require cautious stocking, sufficient space, and close behavior monitoring.
  • Territorial footprint and swimming zone overlap require extra space and cover.
  • Breeding aggression can turn an otherwise workable pairing into a caution setup.

Supporting factors

  • Temperature ranges overlap well.
  • pH requirements overlap well.
American Flagfish profileGreen Severum profileMethodology and limitations

Why This Pair Received Its Verdict

American Flagfish and Green Severum receive a not recommended verdict from the current structured assessment. American Flagfish is recorded as semi-aggressive with an aggression level of 4/10; Green Severum is recorded as semi-aggressive with an aggression level of 5/10. 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.
  • Both species may show territorial behavior.
  • One species should be maintained in a proper school or group.

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. Green Severum is recorded at 75–84°F and pH 6–7.5. Their shared planning window is 75–78°F for temperature and 6.5–7.5 for pH. A shared aquarium must stay inside the overlap rather than merely touching each species’ outer tolerance.

Aquarium Space and Adult Size

Green Severum sets the larger listed base aquarium requirement at 75 gallons; the other listed minimum is 20 gallons. Green Severum is the larger adult by the recorded maximum, reaching 10 inches, compared with 2.5 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. Green Severum 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 green severum does not have a recorded minimum school larger than one. 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 Green Severum is a omnivore with intermediate care. Their listed preferred tank styles are community and community. 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 Green Severum; 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.
  • A different tank mate is the preferred decision for this pair. Attempting the combination transfers the identified risk to the animals rather than resolving it.

Aquarium Planning Checklist

  • Keep temperature within 75–78°F.
  • Keep pH within 6.5–7.5.
  • Use at least the larger 75-gallon base requirement before accounting for the complete stocking plan.
  • American Flagfish should be planned as a group of at least 2; green severum does not have a recorded minimum school larger than one.
  • Choose separate aquariums or a different tank mate instead of attempting to manage a known blocking risk.

Final Recommendation

Do not plan a shared aquarium for this pair. Choose a different tank mate or maintain separate aquariums.

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
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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