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Conditional1 concerns

Kissing gourami and Sailfin molly

Can these two share a tank? The assessment below is derived from stored behavioural and environmental traits, not from a compatibility chart.

VerdictConditionalmoderate confidence

Can work, but only if the stated conditions are met.

Minimum volume
460 L
Minimum length
165 cm
Factors considered
4

Concerns

moderateph

pH ranges overlap only across 7.5–8, which is tighter than most tap-water supplies hold naturally.

Derived from: environment.ph overlap width

Why it can work

  • Temperature requirements overlap comfortably at 22–28 °C, with room for both animals to sit inside their preferred range.
  • Hardness requirements overlap at 12–20 °dGH.
  • The two occupy different levels of the tank, which reduces direct competition for space.

Conditions

Most interesting pairings are conditional on something. These are the things the keeper can actually change.

  • At least 460 L with a footprint of 165 cm or more, before counting anything else in the tank

Derived, or documented?

These are different claims and are shown separately. The verdict above is derived from stored traits — arithmetic on AquariumHQ's own records. Whether the pairing is actually reported to work is a separate question, and for most pairs the honest answer is that we hold nothing.

Environmental compatibility

Derived from stored traits

Temperature, pH, hardness, size and behavioural traits compared between the two records. Sound as far as it goes, and it is not evidence that the pairing works.

Behavioural evidence

No behavioural evidence held

AquariumHQ holds no behavioural evidence for this pairing. The verdict is derived entirely from stored traits — it is arithmetic on our own records, not a report about how the pairing actually goes.

How good is the overlap?

Whether two ranges intersect is a necessary condition, not evidence. What matters is WHERE the shared band sits: an overlap at the top of one animal's range and the bottom of the other's is a forced compromise however wide it looks, and it is the case a simple intersection test cannot see.

Each dimension assessed for the quality of the overlap, not merely its existence.
DimensionAssessmentWhat that means here
TemperatureComfortable for bothThe shared band 22–28 °C sits centrally in both ranges, with room to drift.
pHOne animal at the edge of its rangeThe shared band 7.5–8 pH sits at the top of one animal's range, so that animal is permanently at its limit even though the overlap looks generous.
HardnessWorkableThe shared band 12–20 °dGH is usable, though it does not sit centrally for both animals.

Factor by factor

Every factor states what it rests on. Most are derived from the traits stored on both records — sound arithmetic on AquariumHQ's own data, and not a report about how the pairing actually goes. Where a factor says 'not known', the data is missing and saying so matters, because a missing factor and a favourable one look identical once both are absent.

0 evidence-backed17 derived2 not known
FactorBasisFinding
TemperatureDerived from stored traitsComfortable for both. The shared band 22–28 °C sits centrally in both ranges, with room to drift.
pHDerived from stored traitsOne animal at the edge of its range. The shared band 7.5–8 pH sits at the top of one animal's range, so that animal is permanently at its limit even though the overlap looks generous.
HardnessDerived from stored traitsWorkable. The shared band 12–20 °dGH is usable, though it does not sit centrally for both animals.
Body sizeDerived from stored traitsKissing gourami reaches about 30 cm against 15 cm for Sailfin molly — a ratio of 2.0. Size disparity drives opportunistic predation independently of temperament.
PredationDerived from stored traitsHighest predation risk in either direction is "moderate".
TerritorialityDerived from stored traitsStrongest territoriality across the pair is "mild".
Breeding aggressionDerived from stored traitsBreeding aggression reaches "mild". A pairing peaceful for months can change within a day of a spawn.
Fin-nippingDerived from stored traitsNo nipper-and-target combination between these two.
AggressionDerived from stored traitsStrongest intraspecific aggression across the pair is "moderate". It bears on the pairing because a fish under pressure from its own kind redirects.
Social requirementsDerived from stored traitsNeither animal requires a group.
Group-size dependencyDerived from stored traitsThe outcome does not depend on group size for either animal.
Tank zoneDerived from stored traitsThe two use different levels of the tank, which reduces direct competition for space.
Activity levelDerived from stored traitsActivity levels are compatible.
Food competitionDerived from stored traitsDifferent feeding strategies, so direct competition is limited.
Risk to shrimp and snailsDerived from stored traitsHighest risk either animal poses to dwarf shrimp or snails is "near-certain".
Effect on plantsDerived from stored traitsKissing gourami eats plants, which constrains the aquascape rather than the pairing.
Tank dimensionsDerived from stored traitsThe more demanding of the two needs at least 400 L and 150 cm of length before anything else is in the tank. Volume alone does not describe a home for a fish that swims in straight lines.
Life stageNot knownAquariumHQ holds no record of whether this pairing changes as either animal matures. Stored traits describe adults, so a pairing that fails at adult size looks identical to one that never fails.
Individual variationNot knownAquariumHQ holds no record of how much this pairing varies between individuals. For several species — bettas and cichlids especially — that variation decides the outcome and a species-level verdict cannot express it.

Environmental overlap

ParameterShared rangeReading
Temperature22–28 °CAim for the middle of the shared band.
pH7.5–8Stability matters more than the exact figure.
Hardness12–20 °dGHCheck your source water before committing.

What this assessment cannot tell you

  • Individual temperament varies, particularly in cichlids and in bettas, and can override a favourable verdict for Kissing gourami or Sailfin molly.
  • The assessment is for the pair in isolation. A third species can change the outcome in either direction.
  • Both animals are assessed at adult size, not at the size they are sold.
  • A verdict is a statement about probability, not a guarantee.

The two species