Bristlenose pleco and Clown loach
Can these two share a tank? The assessment below is derived from stored behavioural and environmental traits, not from a compatibility chart.
Usually works. Minor points to watch are listed below.
- Minimum volume
- 1200 L
- Minimum length
- 245 cm
- Factors considered
- 7
Concerns
Temperature requirements overlap at 25–27 °C, though the band does not sit centrally for both animals. Aim for the middle of it and keep the heater accurate.
Derived from: environment.temperature on both records
Bristlenose pleco defends a territory and both animals use the same part of the tank, so give the territory-holder a defensible area away from the main swimming space.
Derived from: traits.territoriality and zone on both records
Both species occupy the bottom of the tank, so allow for the shared space when judging the footprint.
Derived from: zone and traits.activity on both records
Why it can work
- pH requirements overlap at 6–7.5.
- Hardness requirements overlap at 2–12 °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.
- Bristlenose pleco is active mainly after dark, so the two overlap less than the stocking list suggests. Feed the nocturnal animal after lights-out or it will be outcompeted.
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
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
Widely reported in practice
Reported consistently across aquarium practice without a single citable source. Treated as real but not as measurement.
AquariumHQ's overall position
Kept together routinely and the frictions are minor at the sizes fish are sold at. What decides it long-term is that a clown loach is a very large, very long-lived fish, and a tank stocked for the juveniles is wrong within a few years.
What would change it: Enough caves that neither species has to want a specific one, and a tank sized for adult clown loaches from the start.
Factor by factor
- Cave competitionReported
Both species claim caves and both defend them. Clown loaches are reported wedging themselves into occupied pleco caves and the resulting disputes are noisy rather than damaging.
- Adult size of the loachDerived
A clown loach reaches 30 cm and lives for decades. The pairing that works at 8 cm is a different pairing at 30, and it is the loach that changes.
- TemperatureDerived
The clown loach is advised at 25–30 °C and the bristlenose at 22–27. Two degrees of overlap and both animals near an edge.
| Depends on | How much |
|---|---|
| Tank size and dimensions | decisive |
| 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.
| Dimension | Assessment | What that means here |
|---|---|---|
| Temperature | Workable | The shared band 25–27 °C is usable, though it does not sit centrally for both animals. |
| pH | Comfortable for both | The shared band 6–7.5 pH sits centrally in both ranges, with room to drift. |
| Hardness | Workable | The shared band 2–12 °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.
| Factor | Basis | Finding |
|---|---|---|
| Temperature | Derived from stored traits | Workable. The shared band 25–27 °C is usable, though it does not sit centrally for both animals. |
| pH | Derived from stored traits | Comfortable for both. The shared band 6–7.5 pH sits centrally in both ranges, with room to drift. |
| Hardness | Derived from stored traits | Workable. The shared band 2–12 °dGH is usable, though it does not sit centrally for both animals. |
| Body size | Derived from stored traits | Clown loach reaches about 30 cm against 15 cm for Bristlenose pleco — a ratio of 2.0. Size disparity drives opportunistic predation independently of temperament. |
| Predation | Derived from stored traits | Highest predation risk in either direction is "none". |
| Territoriality | Derived from stored traits | Strongest territoriality across the pair is "moderate". |
| 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 "moderate". 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 | Both occupy the bottom of the tank, so the shared space is under pressure. |
| 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. A clown loach reaches 30 cm and lives for decades. The pairing that works at 8 cm is a different pairing at 30, and it is the loach that changes. |
| Individual variation | Evidence-backed | Individual variation: minor. |
Environmental overlap
| Parameter | Shared range | Reading |
|---|---|---|
| Temperature | 25–27 °C | Aim for the middle of the shared band. |
| pH | 6–7.5 | Stability matters more than the exact figure. |
| Hardness | 2–12 °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 Bristlenose pleco or Clown loach.
- 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.
Where the two water bands meet
Derived from the ranges AquariumHQ publishes for each species. The compatibility engine reads the same numbers; this is what they look like drawn on one axis.
Temperature (°C)
Scale: 0 to 36 °C.
pH (pH)
Scale: 4 to 9.5 pH.
Hardness (°dGH)
Scale: 0 to 30 °dGH.
Why the bands sit where they do
The overlap above is arithmetic. This is where the two numbers came from — the kind of water each animal is recorded from, and how much room that leaves.
Both animals come from lowland floodplain, which is why the bands below sit where they do.
Bristlenose pleco
Lowland floodplain
40–300 µS/cm · still flow · low oxygen
Clown loach
Lowland floodplain
40–300 µS/cm · still flow · low oxygen
- TemperatureBristlenose pleco 22–27°CClown loach 25–30°C
Both inside their range from 25–27°C — 40% of the narrower animal’s range.
A real window, and a narrow one. The tank has to be held inside it, and there is little room for the drift that happens between water changes.
- pHBristlenose pleco 6–7.8Clown loach 6–7.5
Both inside their range from 6–7.5 — 100% of the narrower animal’s range.
A wide window. Both animals are inside their own range across most of it, and the tank can be run without either sitting at an edge.
- General hardnessBristlenose pleco 2–20 dGHClown loach 2–12 dGH
Both inside their range from 2–12 dGH — 100% of the narrower animal’s range.
A wide window. Both animals are inside their own range across most of it, and the tank can be run without either sitting at an edge.
Computed from the ranges AquariumHQ publishes for each species, each of which records what it rests on — a source value, a habitat inference, a physiological requirement or a trade convention. Most are habitat inferences, and the species pages say which.