Poor match3 concerns

Clown loach and Mystery snail

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

VerdictPoor matchmoderate confidence

Workable only in unusual circumstances. Not a pairing to plan around.

Minimum volume: 800 L
Minimum length: 200 cm
Factors considered: 6

Concerns

majorinvertebrate risk

Clown loach eats snails. This is sometimes wanted and sometimes not — it applies equally to a snail you paid for and a snail you were trying to remove.

Derived from: traits.predation.snails

moderatetemperature

The shared band 25–28 °C sits at the top of one animal's range, so that animal is permanently at its limit even though the overlap looks generous. The overlap sits at the extreme of at least one animal's range, so that animal is permanently at its limit. A non-empty overlap is not the same as a suitable one.

Derived from: environment.temperature range position on both records

moderateph

pH ranges overlap only across 7–7.5, which is tighter than most tap-water supplies hold naturally.

Derived from: environment.ph overlap width

Why it can work

Hardness requirements overlap at 8–12 °dGH.
Clown loach needs a group of at least 5. Kept in smaller numbers it is not simply lonely — shoaling species held below their threshold show chronic stress behaviour, colour loss and, in several species, increased aggression towards tankmates.
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 5 Clown loach, counted as one group
At least 800 L with a footprint of 200 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

Documented

Reported in husbandry or veterinary sources rather than derived from stored traits.

AquariumHQ's overall position

Incompatible if the snail is wanted. The documented evidence here is unusually clear because the behaviour is the reason the fish is sold.

Factor by factor

Snail predationReported
Loaches of several genera eat snails, and this is frequently the reason they are bought. It applies equally to a snail somebody paid for and a snail somebody was trying to remove.
Adult size of the loachReported
Clown loaches reach a size that surprises most keepers, and a larger loach deals with a larger snail.

What the answer depends on. A single cell in a compatibility chart cannot hold any of these.
Depends on	How much
Tank size and dimensions	none
Life stage	significant
The individual animal	minor

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.
Dimension	Assessment	What that means here
Temperature	One animal at the edge of its range	The shared band 25–28 °C sits at the top of one animal's range, so that animal is permanently at its limit even though the overlap looks generous.
pH	Forced compromise — neither animal is where it wants to be	The shared band 7–7.5 pH sits at the top of one animal's range and the bottom of the other's. Both would be kept at their limits to accommodate the other.
Hardness	One animal at the edge of its range	The shared band 8–12 °dGH sits at the bottom of one animal's range, so that animal is permanently at its limit even though the overlap looks generous.

Forced compromise — neither animal is where it wants to be

Both animals would be kept at the edge of their ranges to accommodate the other. Nothing here is a recommendation; it is the arithmetic of two incompatible requirements meeting at a point.

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.

3 evidence-backed16 derived0 not known

Factor	Basis	Finding
Temperature	Derived from stored traits	One animal at the edge of its range. The shared band 25–28 °C sits at the top of one animal's range, so that animal is permanently at its limit even though the overlap looks generous.
pH	Derived from stored traits	Forced compromise — neither animal is where it wants to be. The shared band 7–7.5 pH sits at the top of one animal's range and the bottom of the other's. Both would be kept at their limits to accommodate the other.
Hardness	Derived from stored traits	One animal at the edge of its range. The shared band 8–12 °dGH sits at the bottom of one animal's range, so that animal is permanently at its limit even though the overlap looks generous.
Body size	Derived from stored traits	Clown loach reaches about 30 cm against 6 cm for Mystery snail — a ratio of 5.0. Size disparity drives opportunistic predation independently of temperament.
Predation	Evidence-backed	Highest predation risk in either direction is "near-certain". Reported: Loaches of several genera eat snails, and this is frequently the reason they are bought. It applies equally to a snail somebody paid for and a snail somebody was trying to remove.
Territoriality	Derived from stored traits	Neither animal holds a territory.
Breeding aggression	Derived from stored traits	Neither becomes notably more aggressive while spawning.
Fin-nipping	Derived from stored traits	No nipper-and-target combination between these two.
Aggression	Derived from stored traits	Strongest intraspecific aggression across the pair is "none". It bears on the pairing because a fish under pressure from its own kind redirects.
Social requirements	Derived from stored traits	Clown loach needs at least 5. A shoaling species held below its threshold shows chronic stress and, in several species, increased aggression towards tankmates.
Group-size dependency	Derived from stored traits	The outcome depends on group size as much as on the pairing: under-grouped shoalers nip more and hide more.
Tank zone	Derived from stored traits	The two use different levels of the tank, which reduces direct competition for space.
Activity level	Derived from stored traits	Activity levels are compatible.
Food competition	Derived from stored traits	Different feeding strategies, so direct competition is limited.
Risk to shrimp and snails	Derived from stored traits	Highest risk either animal poses to dwarf shrimp or snails is "near-certain".
Effect on plants	Derived from stored traits	Neither animal damages planting.
Tank dimensions	Derived from stored traits	The more demanding of the two needs at least 800 L and 200 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 stage	Evidence-backed	Life-stage dependency: significant. Clown loaches reach a size that surprises most keepers, and a larger loach deals with a larger snail.
Individual variation	Evidence-backed	Individual variation: minor.

Environmental overlap

Parameter	Shared range	Reading
Temperature	25–28 °C	Aim for the middle of the shared band.
pH	7–7.5	Stability matters more than the exact figure.
Hardness	8–12 °dGH	Check 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 Clown loach or Mystery snail.
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

Clown loachChromobotia macracanthusSold at 5 cm as a community fish and reaching 30 cm over a slow twenty-year life. It is a large, long-lived, highly social river fish and the great majority of those sold are housed in tanks that will never be adequate.Mystery snailPomacea bridgesiiA large, peaceful, plant-safe apple snail that breathes air through a siphon and lays pink egg clutches above the waterline. It must not be confused with the channelled apple snail, which is a prohibited agricultural pest.