Threadfin Rainbowfish

Iriatherina werneri

Threadfin Rainbowfish is a peaceful top swimmer. Keep in a loose group of 6+.

PeacefulTop swimmerKeep in a loose group of 6+Intermediate

Save this fish or add it directly to one of your aquariums.

Need help with Threadfin Rainbowfish?

Explore compatibility, care or problems using this guide and your aquarium’s conditions.

Quick facts

Adult size: ≤ 1.6" (≤ 4 cm)
Aquarium size: 14 US gal (54 L) or larger / ≥ 23.6" (≥ 60 cm) minimum length
Care level: Intermediate
Temperament: Peaceful
Swimming zone: Top swimmer
Temperature: 72–86°F (22–30°C)
pH: 5–8
GH: 1–12 dGH
KH: 7–10 dKH
Diet: Omnivore
Lifespan: up to 5 years
Group behavior: Keep in a loose group of 6+

Care requirements

Care level: Intermediate.

Lifespan: up to 5 years.

Aquarium size and space needs

Minimum aquarium size: 14 US gal (54 L) or larger / ≥ 23.6" (≥ 60 cm) minimum length. Plan the layout and stocking within that limit.

Water parameters

Suitable water: temperature 22–30 °C, pH 5–8, GH 1–12 dGH, KH 7–10 dKH.

Temperament and compatibility

Threadfin Rainbowfish is peaceful and suits calm community fish.

Beginner friendly: No

Swimming zone and behavior

This fish uses the upper part of the aquarium, so leave enough surface space for movement and feeding.

Feeding

As an omnivore, Threadfin Rainbowfish should receive a varied diet rather than one repeated food type.

Tiny live zooplankton such as Daphnia, Moina, Artemia nauplii, copepods and crushed floating dry feeds.

Before adding this fish

Plan for an aquarium of 14 US gal (54 L) or larger / ≥ 23.6" (≥ 60 cm) minimum length.
Make room for its social group.
Avoid aggressive or highly competitive fish.
Keep in a loose group of 6+.
Offer a varied diet suited to this species’ documented feeding habits.

Natural habitat and origin

Origin: Papua New Guinea Australia.

Similar fish profiles

Use these profiles to compare fish with similar care level, size, temperature range, or swimming behavior.

Aru Rainbowfish Melanotaenia picta Same family Similar care level Same temperament Beginner – Intermediate ≤ 4.3" (≤ 11 cm) 72–79°F (22–26°C) Black Banded Rainbowfish Melanotaenia nigrans Same family Similar care level Same temperament Beginner – Intermediate ≤ 3.9" (≤ 10 cm) 73–82°F (23–28°C) Black Heart Tetra Hyphessobrycon copelandi Similar care level Same temperament Same swimming zone Beginner – Intermediate ≤ 1.6" (≤ 4 cm) 75–82°F (24–28°C) Ajamaru Rainbowfish Melanotaenia ajamaruensis Same family Similar care level Same temperament Beginner – Intermediate ≤ 3.8" (≤ 9.7 cm) 81–86°F (27–30°C) Barred Rainbowfish Chilatherina fasciata Same family Similar care level Same temperament Beginner – Intermediate ≤ 4.3" (≤ 11 cm) 82–90°F (28–32°C) Bleeding Blue Tetra Hyphessobrycon margitae Similar care level Same temperament Same swimming zone Beginner – Intermediate 1.6–2" (4–5 cm) 73–79°F (23–26°C)

FAQ

How large does Threadfin Rainbowfish get?

Threadfin Rainbowfish reaches ≤ 1.6" (≤ 4 cm).

What aquarium size does Threadfin Rainbowfish need?

Use an aquarium of at least 14 US gal (54 L) or larger / ≥ 23.6" (≥ 60 cm) minimum length.

Is Threadfin Rainbowfish peaceful?

Yes. Threadfin Rainbowfish is recorded as peaceful and is best planned with calm community fish that do not harass it or dominate the feeding area.

What temperature is suitable for Threadfin Rainbowfish?

Keep it between 22 to 30 °C.

Is Threadfin Rainbowfish beginner friendly?

Threadfin Rainbowfish is better treated as a planned species for keepers who are already comfortable managing compatibility and water stability.