Can Betta Macrostoma and Congo Bichir Live Together?
Betta Macrostoma and Congo Bichir 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 Betta Macrostoma and Congo Bichir?
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
Betta Macrostoma is a moderately assertive species (6/10), while Congo Bichir is semi-aggressive (7/10). This modest difference means Congo Bichir may occasionally assert dominance over Betta Macrostoma.
Betta Macrostoma and Congo Bichir both frequent the Bottom (Substrate) 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: Congo Bichir is nocturnal and will be most active after lights-out, naturally reducing daytime encounters. Also, Betta Macrostoma is a known jumper, so a tight-fitting lid is essential.
Water Parameters
The safe temperature window for both species falls between 24°C and 25°C. Aim for the midpoint of this range (around 24.5°C) for optimal comfort.
The pH requirements of Betta Macrostoma (4–6) and Congo Bichir (6.5–8) 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.
Tank Setup
To house Betta Macrostoma and Congo Bichir together, plan for an aquarium of at least 800 litres with a minimum length of 200 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: Leaf Litter/Blackwater, Driftwood (Digestion/Hiding), Plants - Floating, Sand (Sifters), Smooth Gravel (Sensitive Barbels). Meeting these requirements will help both species thrive.
Both species do well with low (still water) water movement, so a standard filtration setup rated for the tank volume should suffice.
Why This Pairing Usually Fails in Practice
Betta Macrostoma and Congo Bichir 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 Betta Macrostoma and Congo Bichir live together?
No. This combination is not recommended. Key incompatibilities — such as critical behavioural conflicts — make cohabitation unsafe.
What size tank do Betta Macrostoma and Congo Bichir need?
A minimum of 800 litres (tank length at least 200 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 Betta Macrostoma and Congo Bichir together?
Keep the aquarium between 24°C and 25°C. A target of around 24.5°C sits comfortably within both species' preferred ranges.
Are Betta Macrostoma or Congo Bichir aggressive?
Betta Macrostoma is moderately assertive (6/10) and Congo Bichir is semi-aggressive (7/10). Their similar temperaments generally lead to a peaceful coexistence.
What pH do Betta Macrostoma and Congo Bichir need?
Their pH requirements do not overlap. Betta Macrostoma prefers 4–6, while Congo Bichir needs 6.5–8. 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.
Does Congo Bichir being nocturnal affect compatibility?
Congo Bichir is most active after lights-out, which naturally reduces daytime encounters with its tank mate. This can actually be beneficial, as both fish get undisturbed time to feed and explore. Just ensure food reaches Congo Bichir during evening hours.
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Guidarium Editorial Desk
Reviewed against Guidarium care, stocking, and compatibility standards. Read the editorial policy.
- Last reviewed
- May 3, 2026
- Last updated
- May 3, 2026
- Issues or corrections?
- Contact the editorial team
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