Compatibility Report

Can Cardinal Tetra Live With Pea Puffer?

GuideMyTank compatibility analysis for Cardinal Tetra and Pea Puffer.

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

One species is best planned as a species-only setup.
A species needing stable water has only a narrow pH, GH, or KH overlap.
Specialist tank style requirements need careful matching.

Conditions and cautions

pH ranges have limited overlap.
One species may be semi-aggressive and require planning.
Tank size requirements differ slightly.
Freshwater puffers are specialist fin-nipping hunters and are poor community tankmates.

Supporting factors

Temperature ranges overlap well.
Both species have compatible schooling or group behavior.
No predation risk detected.

Cardinal Tetra profile Pea Puffer profile Methodology and limitations

Why This Pair Received Its Verdict

Cardinal Tetra and Pea Puffer receive a not recommended verdict from the current structured assessment. Cardinal Tetra is recorded as peaceful with an aggression level of 1/10; Pea Puffer 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 ranges have limited overlap.
One species may be semi-aggressive and require planning.
Both species have compatible schooling or group behavior.

Water Parameter Overlap

Cardinal Tetra has a recorded temperature range of 73–84°F and pH range of 5–7. Pea Puffer is recorded at 74–82°F and pH 6.8–8. Their shared planning window is 74–82°F for temperature and 6.8–7 for pH. A shared aquarium must stay inside the overlap rather than merely touching each species’ outer tolerance.

Aquarium Space and Adult Size

Cardinal Tetra sets the larger listed base aquarium requirement at 20 gallons; the other listed minimum is 10 gallons. Cardinal Tetra is the larger adult by the recorded maximum, reaching 2 inches, compared with 1.4 inches. These figures are starting constraints, not a stocking-capacity calculation, because the complete group sizes and bioload still matter.

Behavior and Social Requirements

Cardinal Tetra is a calm species associated with the mid zone and moderate flow. Pea Puffer is moderate, uses the mid zone, and has a moderate flow preference. Cardinal Tetra should be planned as a group of at least 8, while pea puffer should be planned as a group of at least 6. The aquarium must support both social structures without forcing either species into insufficient space.

Husbandry Fit

Cardinal Tetra is recorded as a omnivore with intermediate care, while Pea Puffer is a carnivore with advanced care. Their listed preferred tank styles are blackwater and species_only. 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 Cardinal Tetra and Pea Puffer; 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 74–82°F.
Keep pH within 6.8–7.
Use at least the larger 20-gallon base requirement before accounting for the complete stocking plan.
Cardinal Tetra should be planned as a group of at least 8; pea puffer should be planned as a group of at least 6.
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
thesprucepets.comcare · medium confidence
en.wikipedia.orgtaxonomy · medium confidence
en.wikipedia.orgtaxonomy · medium confidence
en.wikipedia.orgtaxonomy · medium confidence
en.wikipedia.orgtaxonomy · medium confidence
es.wikipedia.orgtaxonomy · medium confidence

Read the full methodology and limitations

Report quality: supported
Analysis version: 2026.09.1
Species data updated: Sep 29, 2026
Review status: Structured automated assessment

Related Resources

Continue with the most relevant care and compatibility resources for Cardinal Tetra and Pea Puffer.