Candidate
Neon tetra
Paracheirodon innesi
A classic soft-water shoal that suits cooler tropical communities.
- Adult
- 3–4 cm
- Minimum
- 60 L · 60 cm
- Group
- 8
Condition-led guide · reviewed 2026-07-31
Peaceful aquarium fish for soft water
A shortlist for naturally low-mineral water, organised around calm shoals and appropriately sized centrepieces.
Selection rules
What made the shortlist
- Confirm GH as well as pH; low pH does not prove soft water.
- Keep shoaling species in one meaningful group.
- Use botanicals for habitat only when their chemistry effect is understood.
Real photographed species
Options worth researching
Choose a temperature band first, then build around one shoal and a compatible zone plan.
Candidate
Cardinal tetra
Paracheirodon axelrodi
A warmer shoal for stable mature systems.
- Adult
- 4–5 cm
- Minimum
- 75 L · 75 cm
- Group
- 8
Candidate
Ember tetra
Hyphessobrycon amandae
A tiny gentle option for calm planted tanks.
- Adult
- 1.5–2 cm
- Minimum
- 45 L · 45 cm
- Group
- 10
Candidate
Chili rasbora
Boraras brigittae
A minute shoaler for mature, species-appropriate nano aquariums.
- Adult
- 1.5–2 cm
- Minimum
- 35 L · 45 cm
- Group
- 10
Candidate
Harlequin rasbora
Trigonostigma heteromorpha
A reliable calm group across a useful soft-to-moderate range.
- Adult
- 4–5 cm
- Minimum
- 60 L · 60 cm
- Group
- 8
Candidate
Honey gourami
Trichogaster chuna
A gentle centrepiece where surface cover and flow suit it.
- Adult
- 4–5 cm
- Minimum
- 60 L · 60 cm
- Group
- 1
Common mismatch
Fish to rule out for this brief
Do not soften water by guessing. Sudden mineral changes can be more harmful than choosing a species suited to the tap.
Think again
Molly
Poecilia sphenops
Its mineral demand is poorly served by persistently soft water.
- Adult
- 6–10 cm
- Minimum
- 75 L · 75 cm
- Group
- 3
Think again
Rabbit snail
Tylomelania gemmifera
Shell health requires substantially more dissolved minerals.
- Adult
- 6–10 cm
- Minimum
- 45 L · 45 cm
- Group
- 1
Think again
Boesemani rainbowfish
Melanotaenia boesemani
Its reviewed hardness range starts well above very soft water.
- Adult
- 7–11 cm
- Minimum
- 200 L · 120 cm
- Group
- 8