Can Asian Arowana and Threadfin Rainbowfish Live Together?

Not Recommended

Asian Arowana and Threadfin Rainbowfish are not recommended as tank mates due to piscivorous fish will prey on nano-sized tank mates.. Housing these species together is likely to result in stress, health problems, or direct harm to one or both fish.


At a Glance

Asian Arowana

Scleropages formosus

Threadfin Rainbowfish

Iriatherina werneri

🐠Family Group
Asian Arowana
Oddballs
Threadfin Rainbowfish
Rainbowfish
Temperament
Asian Arowana
Aggressive (8/10)
Threadfin Rainbowfish
Peaceful (1/10)
Temperature
βœ“ Compatible
Asian Arowana
26–30Β°C
Threadfin Rainbowfish
23–29Β°C
pH Range
βœ“ Compatible
Asian Arowana
6–7.5
Threadfin Rainbowfish
5.5–7.5
Hardness (dGH)
βœ“ Compatible
Asian Arowana
1–12
Threadfin Rainbowfish
1–12
Water Type
βœ“ Compatible
Asian Arowana
Freshwater Only
Threadfin Rainbowfish
Freshwater Only
Flow Preference
βœ“ Compatible
Asian Arowana
Moderate
Threadfin Rainbowfish
Low
Min Tank Volume
Combined: 1000 L
Asian Arowana
1000 L
Threadfin Rainbowfish
60 L
Swimming Level
Shared: 1 zone
Asian Arowana
Top
Threadfin Rainbowfish
TopMiddle
🏷️Behavior Tags
Asian Arowana
Piscivore (Eats small/nano fish)Jumper (Lid Required)Aggressive to same species/look-alikesTerritorial (Defends specific area)Hyperactive / Fast Swimmer
Threadfin Rainbowfish
Nano / Bite-sized (Predation Risk)Shy / Slow Moving (Easily Stressed)Jumper (Lid Required)Hyperactive / Fast SwimmerAggressive Eater (Starves shy fish)
Stocking calculator

Can your tank handle Asian Arowana and Threadfin Rainbowfish?

Compatibility is only part of the answer. Test both fish with your real tank size, current stock, and maintenance needs to see if you have enough space and a safe stocking level before you add them.

Asian Arowana
Threadfin Rainbowfish
Test both in my tank

Behaviour & Temperament

Asian Arowana is a semi-aggressive species (8/10), while Threadfin Rainbowfish is peaceful (1/10). This notable difference means Asian Arowana may occasionally assert dominance over Threadfin Rainbowfish.

Large aggression gap (7 points) between Asian Arowana and Threadfin Rainbowfish increases stress risk for the more peaceful fish.

Asian Arowana and Threadfin Rainbowfish both frequent the Top (Surface) region of the setup. This overlap can increase competition for space, so providing ample room and cover is important to keep both species comfortable.

There is a critical concern: the Piscivore (Eats small/nano fish) behaviour of one fish directly conflicts with the Nano / Bite-sized (Predation Risk) trait of the other β€” piscivorous fish will prey on nano-sized tank mates..

Additional behavioural considerations to keep in mind: Hyperactive swimmers can stress shy, slow-moving species through constant motion.

Worth noting: Asian Arowana is a known jumper, so a tight-fitting lid is essential.

Water Parameters

The safe temperature window for both species falls between 26Β°C and 29Β°C. Aim for the midpoint of this range (around 27.5Β°C) for optimal comfort.

Both fish can tolerate a pH between 6 and 7.5. Maintaining a stable value within this band is more important than hitting an exact number.

For general hardness, the shared comfort zone is 1–12 dGH. Regular testing will ensure conditions stay within this range.

Tank Setup

To house Asian Arowana and Threadfin Rainbowfish together, plan for an aquarium of at least 1000 litres with a minimum length of 240 cm. This recommendation combines the stricter species minimums with a community-load allowance so the pairing has realistic long-term space and filtration headroom.

Providing a mix of open swimming space and sheltered areas with rocks, driftwood, or plants will keep both species comfortable and allow natural behaviour.

Specific environmental needs for this combination include: Smooth Gravel (Sensitive Barbels), Plants - Densely covered, Plants - Floating. Meeting these requirements will help both species thrive.

Both species do well with moderate (standard) water movement, so a standard filtration setup rated for the tank volume should suffice.

Frequently Asked Questions

Can Asian Arowana and Threadfin Rainbowfish live together?

No. This combination is not recommended. Key incompatibilities β€” such as critical behavioural conflicts β€” make cohabitation unsafe.

What size tank do Asian Arowana and Threadfin Rainbowfish need?

A minimum of 1000 litres (tank length at least 240 cm) is recommended. This provides enough space for both species to establish their own areas and reduces the likelihood of territorial disputes.

What water temperature is best for Asian Arowana and Threadfin Rainbowfish together?

Keep the aquarium between 26Β°C and 29Β°C. A target of around 27.5Β°C sits comfortably within both species' preferred ranges.

Are Asian Arowana or Threadfin Rainbowfish aggressive?

Asian Arowana is semi-aggressive (8/10) and Threadfin Rainbowfish is peaceful (1/10). The gap in aggression levels means the calmer fish may experience stress from the more assertive one.

What pH do Asian Arowana and Threadfin Rainbowfish need?

Both species overlap in the 6–7.5 pH range. Consistency is key β€” avoid sudden swings, and test regularly to stay within this window.

How do I manage Asian Arowana's territorial behaviour?

Provide line-of-sight breaks using rocks, driftwood, and dense planting. A larger tank gives Asian Arowana space to claim a territory without encroaching on the other fish's area. Adding dΓ©cor that divides the tank into distinct zones works especially well.


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