Can Asian Arowana and Northern Mountain Swordtail Live Together?
Asian Arowana and Northern Mountain Swordtail are not recommended as tank mates due to no temperature overlap. Housing these species together is likely to result in stress, health problems, or direct harm to one or both fish.
At a Glance
Can your tank handle Asian Arowana and Northern Mountain Swordtail?
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.
Behaviour & Temperament
Asian Arowana is a semi-aggressive species (8/10), while Northern Mountain Swordtail is generally mild-mannered (3/10). This notable difference means Asian Arowana may occasionally assert dominance over Northern Mountain Swordtail.
Asian Arowana and Northern Mountain Swordtail 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.
Worth noting: Asian Arowana is a known jumper, so a tight-fitting lid is essential.
Water Parameters
There is no temperature overlap between Asian Arowana (26–30°C) and Northern Mountain Swordtail (20–25°C). This fundamental mismatch makes long-term cohabitation impractical.
Both fish can tolerate a pH between 7 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 8–12 dGH. Regular testing will ensure conditions stay within this range.
Tank Setup
To house Asian Arowana and Northern Mountain Swordtail 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. 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.
Why This Pairing Usually Fails in Practice
Asian Arowana and Northern Mountain Swordtail are the kind of pair that can look acceptable in a shop but become a maintenance problem at home. The main risk is not a single number in the chart; it is the way incompatible behavior, water needs, or pressure on space compounds over time once both fish are established in the same tank.
Frequently Asked Questions
Can Asian Arowana and Northern Mountain Swordtail live together?
No. This combination is not recommended. Key incompatibilities — such as non-overlapping temperature ranges — make cohabitation unsafe.
What size tank do Asian Arowana and Northern Mountain Swordtail 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 Northern Mountain Swordtail together?
Unfortunately, there is no temperature range that satisfies both species. Asian Arowana requires 26–30°C, while Northern Mountain Swordtail needs 20–25°C.
Are Asian Arowana or Northern Mountain Swordtail aggressive?
Asian Arowana is semi-aggressive (8/10) and Northern Mountain Swordtail is generally mild-mannered (3/10). The gap in aggression levels means the calmer fish may experience stress from the more assertive one.
What pH do Asian Arowana and Northern Mountain Swordtail need?
Both species overlap in the 7–7.5 pH range. Consistency is key — 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 décor that divides the tank into distinct zones works especially well.
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Guidarium Editorial Desk
Reviewed against Guidarium care, stocking, and compatibility standards. Read the editorial policy.
- Last reviewed
- May 7, 2026
- Last updated
- May 7, 2026
- Issues or corrections?
- Contact the editorial team
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