Can Achara Catfish and Dusky Millions Fish Live Together?

Possible with Caution

Keeping Achara Catfish and Dusky Millions Fish together is possible but requires caution due to differing aggression levels. Provide a spacious tank of at least 1500 litres with plenty of hiding spots to reduce stress. Monitor behaviour closely, especially during the first few weeks.


At a Glance

Achara Catfish

Leiarius marmoratus

Dusky Millions Fish

Phalloceros caudimaculatus

🐠Family Group
Achara Catfish
Catfish
Dusky Millions Fish
Livebearers
Temperament
Achara Catfish
Semi-Aggressive (6/10)
Dusky Millions Fish
Peaceful (2/10)
Temperature
✓ Compatible
Achara Catfish
22–28°C
Dusky Millions Fish
16–24°C
pH Range
✓ Compatible
Achara Catfish
6–7.5
Dusky Millions Fish
7–8
Hardness (dGH)
✓ Compatible
Achara Catfish
4–15
Dusky Millions Fish
8–20
Water Type
✓ Compatible
Achara Catfish
Freshwater Only
Dusky Millions Fish
Brackish Tolerant
Flow Preference
✓ Compatible
Achara Catfish
Moderate
Dusky Millions Fish
Low
Min Tank Volume
Combined: 1500 L
Achara Catfish
1500 L
Dusky Millions Fish
40 L
Swimming Level
✓ Different zones
Achara Catfish
Bottom
Dusky Millions Fish
TopMiddle
🏷️Behavior Tags
Achara Catfish
Piscivore (Eats small/nano fish)NocturnalShrimp EaterFry PredatorDigger (Disturbs Substrate)
Dusky Millions Fish
Hyperactive / Fast SwimmerPlant DestroyerFin Nipper
Stocking calculator

Can your tank handle Achara Catfish and Dusky Millions Fish?

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.

Achara Catfish
Dusky Millions Fish
Test both in my tank

Behaviour & Temperament

Achara Catfish is a moderately assertive species (6/10), while Dusky Millions Fish is peaceful (2/10). This notable difference means Achara Catfish may occasionally assert dominance over Dusky Millions Fish.

In terms of spatial distribution, Achara Catfish prefers the Bottom (Substrate) zone, whereas Dusky Millions Fish occupies the Top (Surface) and Middle (Open Water) zones. Because they use different levels of the water column, territorial disputes are less likely and the tank will appear more balanced.

Worth noting: Achara Catfish is nocturnal and will be most active after lights-out, naturally reducing daytime encounters.

To improve the chances of a peaceful coexistence in this community tank: A larger aquarium with ample hiding spots can help diffuse aggression and give the less dominant fish space to retreat. Keep fin nippers in larger groups to distribute nipping behaviour among conspecifics rather than tank mates.

Water Parameters

The safe temperature window for both species falls between 22°C and 24°C. Aim for the midpoint of this range (around 23.0°C) for optimal comfort.

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 8–15 dGH. Regular testing will ensure conditions stay within this range.

Tank Setup

To house Achara Catfish and Dusky Millions Fish together, plan for an aquarium of at least 1500 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.

Because this pairing requires extra vigilance, include plenty of hiding spots — caves, driftwood, and dense plant clusters — so the less dominant fish can retreat when needed.

Specific environmental needs for this combination include: Sand (Sifters), Smooth Gravel (Sensitive Barbels), Driftwood (Digestion/Hiding), Plants - Densely covered, Plants - Floating, Established Algae (Otocinclus). 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 Achara Catfish and Dusky Millions Fish live together?

They can coexist, but the pairing requires careful monitoring. Provide ample space (at least 1500 litres), plenty of hiding spots, and watch for signs of stress or aggression.

What size tank do Achara Catfish and Dusky Millions Fish need?

A minimum of 1500 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 Achara Catfish and Dusky Millions Fish together?

Keep the aquarium between 22°C and 24°C. A target of around 23.0°C sits comfortably within both species' preferred ranges.

Are Achara Catfish or Dusky Millions Fish aggressive?

Achara Catfish is moderately assertive (6/10) and Dusky Millions Fish is peaceful (2/10). The gap in aggression levels means the calmer fish may experience stress from the more assertive one.

What pH do Achara Catfish and Dusky Millions Fish 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.

Will Dusky Millions Fish nip Achara Catfish's fins?

Dusky Millions Fish is a known fin nipper. If Achara Catfish 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 Achara Catfish being nocturnal affect compatibility?

Achara Catfish 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 Achara Catfish during evening hours.


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