Species profile
Threadfin Rainbowfish
Iriatherina werneri
Peaceful
Moderate care
80 L minimum aquarium
4–5 cm adult size
Top mid
Minimum group: 8
About this species
General notes for hobby use.
Delicate, slow-feeding rainbowfish. Long-finned males and tiny mouths make calm tankmates and small foods essential.
Water parameters
Suggested general range for long-term care.
Temperature
23–28 °C
pH
5.2–7
GH
1–12 dGH
KH
Not yet documented
Flow preference
Low–moderate
Data confidence
Verified
Behaviour
General behaviour traits used by TanksConnected compatibility checks.
Minimum group size
Minimum group: 8
Tank zone
Top mid
Territory level
None
Predation risk
Tiny fry
Bioload factor
0.5
Peaceful shoaler; males display dramatically without serious injury when enough space and females are present.
Compatibility flags
Quick cautions for common tank-planning issues.
Fin nipper
No
Plant safe
Yes
Shrimp safe
Yes
Snail safe
Yes
Cave breeder
No
Digs substrate
No
Jump risk
Yes
Natural history & care
Research-backed context for long-term aquarium care.
Lifespan
Not yet documented
Diet type
Omnivore
Minimum aquarium volume
80 L
Minimum footprint
80 × 30 cm
Accepted scientific name
Iriatherina werneri
Alternative names
Threadfin Rainbowfish, Featherfin Rainbowfish
Native range
Southern New Guinea and northern Australia.
Natural habitat
Slow creeks, swamps and vegetated lowland waters. Dense plants, gentle flow and calm surface conditions work well.
Diet & feeding
Tiny live/frozen foods and small quality dry foods; they compete poorly with fast feeders.
Breeding & sexing
Research-backed guidance for identifying sexes and reproductive behaviour.
Sexing
Males develop greatly elongated dorsal/anal fin rays and stronger colour; females have shorter fins.
Breeding
Eggs are scattered/deposited among fine plants or spawning mops over many days; parents may eat eggs/fry.