Can Dusky Millions Fish and Ornate Bichir Live Together?
Dusky Millions Fish and Ornate Bichir 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 Dusky Millions Fish and Ornate 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
Dusky Millions Fish is a peaceful species (2/10), while Ornate Bichir is moderately assertive (6/10). This notable difference means Ornate Bichir may occasionally assert dominance over Dusky Millions Fish.
In terms of spatial distribution, Dusky Millions Fish prefers the Top (Surface) and Middle (Open Water) zones, whereas Ornate Bichir occupies the Bottom (Substrate) zone. Because they use different levels of the water column, territorial disputes are less likely and the tank will appear more balanced.
Worth noting: Ornate Bichir is nocturnal and will be most active after lights-out, naturally reducing daytime encounters. Also, Ornate Bichir is a known jumper, so a tight-fitting lid is essential.
Water Parameters
There is no temperature overlap between Dusky Millions Fish (16–24°C) and Ornate Bichir (26–30°C). This fundamental mismatch makes long-term cohabitation impractical.
Both fish can tolerate a pH between 7 and 8. Maintaining a stable value within this band is more important than hitting an exact number.
For general hardness, the shared comfort zone is 8–20 dGH. Regular testing will ensure conditions stay within this range.
Tank Setup
To house Dusky Millions Fish and Ornate Bichir together, plan for an aquarium of at least 680 litres with a minimum length of 180 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 - Densely covered, Plants - Floating, Established Algae (Otocinclus), Sand (Sifters), Driftwood (Digestion/Hiding), 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
Dusky Millions Fish and Ornate 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.
Suitable Tank Sizes
Standard aquarium sizes large enough for both Dusky Millions Fish and Ornate Bichir.
Frequently Asked Questions
Can Dusky Millions Fish and Ornate Bichir live together?
No. This combination is not recommended. Key incompatibilities — such as non-overlapping temperature ranges — make cohabitation unsafe.
What size tank do Dusky Millions Fish and Ornate Bichir need?
A minimum of 680 litres (tank length at least 180 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 Dusky Millions Fish and Ornate Bichir together?
Unfortunately, there is no temperature range that satisfies both species. Dusky Millions Fish requires 16–24°C, while Ornate Bichir needs 26–30°C.
Are Dusky Millions Fish or Ornate Bichir aggressive?
Dusky Millions Fish is peaceful (2/10) and Ornate Bichir 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 Dusky Millions Fish and Ornate Bichir need?
Both species overlap in the 7–8 pH range. Consistency is key — avoid sudden swings, and test regularly to stay within this window.
Will Dusky Millions Fish nip Ornate Bichir's fins?
Dusky Millions Fish is a known fin nipper. If Ornate Bichir has long or flowing fins, there is a real risk of fin damage. Keeping Dusky Millions Fish in a larger group can help redirect nipping behaviour toward conspecifics.
Does Ornate Bichir being nocturnal affect compatibility?
Ornate 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 Ornate Bichir during evening hours.
Shared setup supplies
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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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