Is the zebra danio a tropical fish?
It is sold as one, kept as one, and the sources do not support it. This is also the case study where AquariumHQ's previous account of the evidence turned out to be wrong about which source said what.
The question
Should a zebra danio be kept at the temperature a general community aquarium runs at?
The evidence, live
Rendered from AquariumHQ's evidence layer rather than restated in prose, so this page cannot drift from the data behind it. If a value is corrected, what you see here changes.
Why we say this
What each source reports for Zebra danio — temperature.
What each source reports
| Source | Value | What kind of value | Published at | Checked |
|---|---|---|---|---|
| AquariumHQ husbandry synthesis | 18–24 °C | Recommended for keeping | Published for this species | 2026-08-11 |
| FishBase | 18–24 °C | Tolerated range | Published for this species | 2026-08-11 |
| Ornamental Aquatic Trade Association | 17–27 °C | Recommended for keeping | Published for the genus | 2026-08-11 |
| Ornamental Aquatic Trade Association | 17–17 °C | Stated minimum | Published for a trade grouping, not this species | 2026-08-11 |
How AquariumHQ read them
The sources overlap across most of the span they collectively cover. The shared band is well supported.
2 sources collectively span 17–27 °C and all of them include 18–24 °C — 60 % of the collective span. AquariumHQ publishes the shared band, which is the range every source agrees on, rather than an average of their midpoints. Not every source publishes at species level: 1 published for this species, 1 published for the genus. A group-level care sheet is evidence about the group, not a species-level measurement. Values answering different questions are recorded separately (stated minimum, tolerated range) and are not merged into this band.
Withdrawn on checking
AquariumHQ previously recorded these and, on opening the source, found it publishes no value of this kind. They are shown rather than deleted, because a correction nobody can see is indistinguishable from never having erred.
- UF/IFAS Extension — fish health and aquaculture publications — 24–28 °C: No UF/IFAS publication AquariumHQ could locate gives a zebra danio temperature recommendation. The figure was invented in Mega Sprint 2 to serve as the warm-keeping outlier in a narrative, and the narrative did not need it: the genuine disagreement is between AquariumHQ and OATA's upper bound, not with a fabricated extension source.
Last reviewed 2026-08-11
Why we say this
Cardinal tetra, for contrast
What each source reports
| Source | Value | What kind of value | Published at | Checked |
|---|---|---|---|---|
| AquariumHQ husbandry synthesis | 24–28 °C | Recommended for keeping | Published for this species | 2026-08-11 |
| FishBase | 23–27 °C | Tolerated range | Published for this species | 2026-08-11 |
| Ornamental Aquatic Trade Association | 22–27 °C | Recommended for keeping | Published for a trade grouping, not this species | 2026-08-11 |
How AquariumHQ read them
The sources overlap, but each covers ground the others do not. The shared band is narrower than any single source suggests.
2 sources collectively span 22–28 °C and all of them include 24–27 °C — 50 % of the collective span. AquariumHQ publishes the shared band, which is the range every source agrees on, rather than an average of their midpoints. Not every source publishes at species level: 1 published for this species, 1 published for a trade grouping, not this species. A group-level care sheet is evidence about the group, not a species-level measurement. Values answering different questions are recorded separately (tolerated range) and are not merged into this band.
Why we say this
Neon tetra, for contrast
What each source reports
| Source | Value | What kind of value | Published at | Checked |
|---|---|---|---|---|
| AquariumHQ husbandry synthesis | 21–25 °C | Recommended for keeping | Published for this species | 2026-08-11 |
| FishBase | 20–26 °C | Tolerated range | Published for this species | 2026-08-11 |
| Ornamental Aquatic Trade Association | 22–27 °C | Recommended for keeping | Published for a trade grouping, not this species | 2026-08-11 |
How AquariumHQ read them
The sources overlap, but each covers ground the others do not. The shared band is narrower than any single source suggests.
2 sources collectively span 21–27 °C and all of them include 22–25 °C — 50 % of the collective span. AquariumHQ publishes the shared band, which is the range every source agrees on, rather than an average of their midpoints. Not every source publishes at species level: 1 published for this species, 1 published for a trade grouping, not this species. A group-level care sheet is evidence about the group, not a species-level measurement. Values answering different questions are recorded separately (tolerated range) and are not merged into this band.
“Tropical fish” is not a thermal category
Aquarium retail divides fish into tropical and coldwater, and the division is commercial rather than biological. It describes which tank a fish is displayed in and which heater a customer is sold, and it groups together animals whose thermal requirements differ by more than ten degrees.
The zebra danio comes from seasonally variable water in the Indian subcontinent, where winter temperatures fall well below anything a community heater is set to. It is sold alongside cardinal tetras from equatorial blackwater that never cools. Both are labelled tropical, and a single tank cannot suit both.
The consequence is not dramatic and that is what makes it persistent. A danio kept warm does not die visibly; it lives faster. Metabolic rate rises with temperature, and a fish held permanently at the top of its range is running an engine harder than it was built for.
What the sources actually say
Three positions are recorded, and they are shown live below rather than quoted here, so that this page cannot drift from the data behind it.
The important structural point is that they are not all answering the same question. A biodiversity database publishes an environmental range derived from where the species occurs; a trade body publishes a keeping recommendation; a floor for unheated tanks is a different statement again. AquariumHQ groups by what a value is FOR before comparing anything, which is why one of these appears separately as context rather than as a rival figure.
Where the previous account was wrong
Mega Sprint 2 built this case study around a claim that FishBase gave the zebra danio a tolerance of 6–38 °C, and cast that very wide range as the sort of figure used to justify keeping the fish warm.
Mega Sprint 3 opened FishBase. It gives 18–24 °C — which is not a wide tolerance at all, and which agrees with AquariumHQ's own recommendation rather than undermining it.
So the conclusion survived and the reasoning did not. The cool position is better supported than the sprint arguing for it realised, and the source it had cast as the opposition was on its side. The original figure has been corrected in the dataset and the superseded value is retained, so this correction is itself inspectable.
What this changes in a tank
A zebra danio does not need a heater in a room that stays above about 17 °C, and the trade body that publishes a suitable-species list for unheated aquariums includes it on that list.
The practical difficulty is not the danio. It is that almost everything else sold in the same aisle does need warmth, so keeping danios properly means building a tank around them rather than adding them to a community. That is a harder recommendation to act on than a number, and it is the honest one.
What AquariumHQ concludes
Stated as a position rather than as a fact, because that is what it is.
- AquariumHQ keeps the zebra danio at the cool end of the community range and states it as a recommendation rather than a tolerance.
- The sources that address the keeping question agree more closely than the hobby's tropical/coldwater split implies.
- A tank suiting both a zebra danio and a warm-water species is a compromise for at least one of them, and AquariumHQ's compatibility engine now reports that rather than reporting that the ranges overlap.
What this still cannot establish
Published rather than omitted. A case study with no stated limits has not had its limits looked for.
- AquariumHQ holds no evidence about lifespan outcomes at different temperatures for this species. The metabolic argument is general physiology, not a measured result for Danio rerio, and it is not presented as one.
- No value here is a controlled comparison. They are published positions from three sources, two of which have not stated how they arrived at their figures.
- The values marked as recorded from trade guidance are published at genus or group level rather than for this species specifically.