Candidate
White cloud mountain minnow
Tanichthys albonubes
A social subtropical fish for well-oxygenated planted tanks.
- Adult
- 3–4 cm
- Minimum
- 45 L · 60 cm
- Group
- 8
Condition-led guide · reviewed 2026-07-31
Cooler-water community fish
Fish that can be planned below standard tropical heat, with oxygen and seasonal room temperature considered.
Selection rules
What made the shortlist
- Use the warmest summer room temperature, not only the winter reading.
- Provide strong oxygenation as water warms.
- Every species in the community must share an actual temperature overlap.
Real photographed species
Options worth researching
Build around summer maximum, winter minimum and oxygen delivery rather than the label 'unheated'.
Candidate
Zebra danio
Danio rerio
An active cooler-water shoaler that needs a long swim lane.
- Adult
- 4–5 cm
- Minimum
- 60 L · 75 cm
- Group
- 8
Candidate
Pearl danio
Danio albolineatus
A fast social fish with a broad cooler tropical range.
- Adult
- 5–6 cm
- Minimum
- 75 L · 90 cm
- Group
- 8
Candidate
Rosy barb
Pethia conchonius
A larger active barb for appropriately long aquariums.
- Adult
- 10–15 cm
- Minimum
- 100 L · 100 cm
- Group
- 8
Candidate
Gold barb
Barbodes semifasciolatus
A social midwater option that remains comfortable below high tropical temperatures.
- Adult
- 6–8 cm
- Minimum
- 90 L · 90 cm
- Group
- 8
Candidate
Peppered corydoras
Corydoras paleatus
A bottom group that tolerates cooler water than many corys.
- Adult
- 5–7 cm
- Minimum
- 75 L · 80 cm
- Group
- 6
Common mismatch
Fish to rule out for this brief
Cool-water does not mean no heater; a thermostat can prevent dangerous cold swings without running tropical-hot.
Think again
Discus
Symphysodon aequifasciatus
Its specialist warm range has no useful overlap.
- Adult
- 15–20 cm
- Minimum
- 300 L · 120 cm
- Group
- 6
Think again
German blue ram
Mikrogeophagus ramirezi
It requires consistently high tropical temperatures.
- Adult
- 5–7 cm
- Minimum
- 75 L · 60 cm
- Group
- 1
Think again
Sterbai corydoras
Corydoras sterbai
This cory is selected specifically for warm conditions.
- Adult
- 6–7 cm
- Minimum
- 75 L · 80 cm
- Group
- 6