Can Australian Smelt and Betta Macrostoma Live Together?
Australian Smelt and Betta Macrostoma are not recommended as tank mates due to conflicting pH requirements. 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 Australian Smelt and Betta Macrostoma?
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.
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Behaviour & Temperament
Australian Smelt is a peaceful species (1/10), while Betta Macrostoma is moderately assertive (6/10). This notable difference means Betta Macrostoma may occasionally assert dominance over Australian Smelt.
Australian Smelt and Betta Macrostoma both frequent the Top (Surface) and Middle (Open Water) region of the setup. This overlap can increase competition for space, so providing ample room and cover is important to keep both species comfortable.
Additional behavioural considerations to keep in mind: Hyperactive swimmers can stress shy, slow-moving species through constant motion.
Worth noting: Australian Smelt is a known jumper, so a tight-fitting lid is essential.
Water Parameters
The safe temperature window for both species falls between 20°C and 24°C. Aim for the midpoint of this range (around 22.0°C) for optimal comfort.
The pH requirements of Australian Smelt (6.5–8) and Betta Macrostoma (4–6) do not overlap, making it impossible to satisfy both species simultaneously.
For general hardness, the shared comfort zone is 5–5 dGH. Regular testing will ensure conditions stay within this range.
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Tank Setup
To house Australian Smelt and Betta Macrostoma together, plan for an aquarium of at least 80 litres with a minimum length of 60 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: Plants - lighly covered, Smooth Gravel (Sensitive Barbels), Leaf Litter/Blackwater, Driftwood (Digestion/Hiding), 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.
Suitable Tank Sizes
Standard aquarium sizes large enough for both Australian Smelt and Betta Macrostoma.
29 Gallon Standard
30 Gallon Breeder
36 Gallon Bowfront
40 Gallon Breeder
55 Gallon Standard
60 Gallon Breeder
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Frequently Asked Questions
Can Australian Smelt and Betta Macrostoma live together?
No. This combination is not recommended. Key incompatibilities — such as critical behavioural conflicts — make cohabitation unsafe.
What size tank do Australian Smelt and Betta Macrostoma need?
A minimum of 80 litres (tank length at least 60 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 Australian Smelt and Betta Macrostoma together?
Keep the aquarium between 20°C and 24°C. A target of around 22.0°C sits comfortably within both species' preferred ranges.
Are Australian Smelt or Betta Macrostoma aggressive?
Australian Smelt is peaceful (1/10) and Betta Macrostoma is moderately assertive (6/10). The gap in aggression levels means the calmer fish may experience stress from the more assertive one.
What pH do Australian Smelt and Betta Macrostoma need?
Their pH requirements do not overlap. Australian Smelt prefers 6.5–8, while Betta Macrostoma needs 4–6. This makes them incompatible in the same water chemistry.
How do I manage Betta Macrostoma's territorial behaviour?
Provide line-of-sight breaks using rocks, driftwood, and dense planting. A larger tank gives Betta Macrostoma 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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