Angelfish and Silver dollar
Can these two share a tank? The assessment below is derived from stored behavioural and environmental traits, not from a compatibility chart.
Can work, but only if the stated conditions are met.
- Minimum volume
- 450 L
- Minimum length
- 195 cm
- Factors considered
- 7
Concerns
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
Angelfish 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 midwater 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
- Temperature requirements overlap comfortably at 24–28 °C, with room for both animals to sit inside their preferred range.
- pH requirements overlap at 6–7.2.
- Hardness requirements overlap at 2–12 °dGH.
- Silver dollar 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.
Conditions
Most interesting pairings are conditional on something. These are the things the keeper can actually change.
- At least 5 Silver dollar, counted as one group
- At least 450 L with a footprint of 195 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
Generally compatible as animals, and a poor combination for a planted tank. This is a pairing where the constraint is the aquascape rather than either fish, which is unusual enough to be worth stating plainly.
Factor by factor
- Shared water and temperamentDerived
Both are deep-bodied Amazonian fish wanting soft warm water, and neither is a predator of the other at adult size. The environmental and behavioural fit is genuinely good.
- PlantsReported
The silver dollar is close to entirely herbivorous and will strip a planted tank. Angelfish are usually kept in planted tanks, so the pairing works for the fish and not for the aquascape.
- Group size and startleReported
Silver dollars shoal and crash into hardscape when startled. A group of them in a tank with a slower deep-bodied fish is more disruptive than their temperament suggests.
| Depends on | How much |
|---|---|
| Tank size and dimensions | significant |
| Life stage | minor |
| 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 | Comfortable for both | The shared band 6–7.2 pH sits centrally in both ranges, with room to drift. |
| Hardness | Comfortable for both | The shared band 2–12 °dGH sits centrally in both ranges, with room to drift. |
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 | Comfortable for both. The shared band 6–7.2 pH sits centrally in both ranges, with room to drift. |
| Hardness | Derived from stored traits | Comfortable for both. The shared band 2–12 °dGH sits centrally in both ranges, with room to drift. |
| Body size | Derived from stored traits | Adult sizes are comparable at about 15 cm and 15 cm, so neither is a mouthful for the other. |
| Predation | Derived from stored traits | Highest predation risk in either direction is "high". |
| 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 | 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 | Silver dollar 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 | Evidence-backed | The outcome depends on group size as much as on the pairing: under-grouped shoalers nip more and hide more. Reported: Silver dollars shoal and crash into hardscape when startled. A group of them in a tank with a slower deep-bodied fish is more disruptive than their temperament suggests. |
| Tank zone | Derived from stored traits | Both occupy the midwater 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 | Evidence-backed | Silver dollar eats plants, which constrains the aquascape rather than the pairing. Reported: The silver dollar is close to entirely herbivorous and will strip a planted tank. Angelfish are usually kept in planted tanks, so the pairing works for the fish and not for the aquascape. |
| Tank dimensions | Derived from stored traits | The more demanding of the two needs at least 300 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 stage | Evidence-backed | Life-stage dependency: minor. See the documented record. |
| 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 | 6–7.2 | 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 Angelfish or Silver dollar.
- 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
Silver dollar
Clearwater lowland river
20–100 µS/cm · moderate flow · near saturation oxygen
- TemperatureAngelfish 24–29°CSilver dollar 24–28°C
Both inside their range from 24–28°C — 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.
- pHAngelfish 6–7.5Silver dollar 5.5–7.2
Both inside their range from 6–7.2 — 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.
- General hardnessAngelfish 2–15 dGHSilver dollar 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.