Angelfish and Guppy
Can these two share a tank? The assessment below is derived from stored behavioural and environmental traits, not from a compatibility chart.
Workable only in unusual circumstances. Not a pairing to plan around.
- Minimum volume
- 270 L
- Minimum length
- 130 cm
- Factors considered
- 8
Concerns
pH ranges overlap only across 7–7.5, which is tighter than most tap-water supplies hold naturally.
Derived from: environment.ph overlap width
Angelfish harasses slow-moving or long-finned tankmates, and Guppy fits that description. Persistent harassment shows up as hiding, clamped fins and refusal to feed long before it shows up as injury.
Derived from: traits.predation.harassment and traits on the second record
Angelfish may nip trailing fins, and Guppy carries the kind of fins that get nipped. Damaged fins are also an entry point for secondary infection, so this is a welfare issue rather than a cosmetic one.
Derived from: traits.finNipping and traits.vulnerableFins
Angelfish becomes markedly more aggressive while spawning. A pairing that has been peaceful for months can change within a day, so plan for where the other animal goes if it does.
Derived from: traits.breedingAggression
Why it can work
- Temperature requirements overlap comfortably at 24–28 °C, with room for both animals to sit inside their preferred range.
- Hardness requirements overlap at 8–15 °dGH.
- Guppy needs a group of at least 6. 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.
- Keep Angelfish in a group of at least 1 — nipping increases sharply in under-sized groups
- At least 6 Guppy, counted as one group
- At least 270 L with a footprint of 130 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
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
A pairing that fails on a delay, and the delay is long enough to be mistaken for success. Tank size does not help — a bigger tank contains a bigger angelfish sooner.
What would change it: Nothing. This is a size and chemistry mismatch that grows into itself.
Factor by factor
- Predation on adultsReported
An adult angelfish takes guppies. Reports are consistent and the mechanism is uncomplicated: a 15 cm cichlid and a 3 cm fish with trailing fins.
- Water chemistryDerived
The angelfish is a soft-water Amazonian fish and the guppy a hard-water one. Even setting predation aside, the two want different water and only one of them can have it.
- The delayDerived
A young angelfish is the size of a coin and ignores guppies entirely. The pairing works for months and then stops, which is why it keeps being recommended by people for whom it has not yet failed.
| Depends on | How much |
|---|---|
| Tank size and dimensions | minor |
| Life stage | decisive |
| 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 | Comfortable for both | The shared band 24–28 °C sits centrally in both ranges, with room to drift. |
| 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 | Workable | The shared band 8–15 °dGH is usable, though it does not sit centrally for both animals. |
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.
| Factor | Basis | Finding |
|---|---|---|
| Temperature | Derived from stored traits | Comfortable for both. The shared band 24–28 °C sits centrally in both ranges, with room to drift. |
| 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 | Workable. The shared band 8–15 °dGH is usable, though it does not sit centrally for both animals. |
| Body size | Derived from stored traits | Angelfish reaches about 15 cm against 6 cm for Guppy — a ratio of 2.5. Size disparity drives opportunistic predation independently of temperament. |
| Predation | Evidence-backed | Highest predation risk in either direction is "high". Reported: An adult angelfish takes guppies. Reports are consistent and the mechanism is uncomplicated: a 15 cm cichlid and a 3 cm fish with trailing fins. |
| Territoriality | Derived from stored traits | Strongest territoriality across the pair is "moderate". |
| Breeding aggression | Derived from stored traits | Breeding aggression reaches "strong". A pairing peaceful for months can change within a day of a spawn. |
| Fin-nipping | Derived from stored traits | One animal nips trailing fins and the other carries the kind of fins that get nipped. Damaged fins are an entry point for secondary infection, so this is a welfare matter rather than a cosmetic one. |
| 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 | Guppy needs at least 6. 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 200 L and 100 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: decisive. An adult angelfish takes guppies. Reports are consistent and the mechanism is uncomplicated: a 15 cm cichlid and a 3 cm fish with trailing fins. |
| Individual variation | Evidence-backed | Individual variation: minor. |
Environmental overlap
| Parameter | Shared range | Reading |
|---|---|---|
| Temperature | 24–28 °C | Aim for the middle of the shared band. |
| pH | 7–7.5 | Stability matters more than the exact figure. |
| Hardness | 8–15 °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 Angelfish or Guppy.
- 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.
These two animals come from different kinds of water, and that is where the arithmetic below comes from rather than from anything about their temperaments.
Angelfish
Lowland floodplain
40–300 µS/cm · still flow · low oxygen
Guppy
No wild referent
variable flow · not characteristic oxygen
- TemperatureAngelfish 24–29°CGuppy 22–28°C
Both inside their range from 24–28°C — 80% 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.
- pHAngelfish 6–7.5Guppy 7–8.5
Both inside their range from 7–7.5 — 33% 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.
- General hardnessAngelfish 2–15 dGHGuppy 8–25 dGH
Both inside their range from 8–15 dGH — 54% 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.
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.