Can Black Pacu and Scat (Brackish) Live Together?

🔴Not Recommended

Black Pacu and Scat (Brackish) are not recommended as tank mates due to incompatible water types. Housing these species together is likely to result in stress, health problems, or direct harm to one or both fish.


At a Glance

Black Pacu

Colossoma macropomum

Scat (Brackish)

Scatophagus argus

🐠Family Group
Black Pacu
Characins
Scat (Brackish)
Oddballs
Temperament
Black Pacu
Mostly Peaceful (4/10)
Scat (Brackish)
Mostly Peaceful (4/10)
Temperature
✓ Compatible
Black Pacu
22–28°C
Scat (Brackish)
20–28°C
pH Range
✓ Compatible
Black Pacu
6–7.5
Scat (Brackish)
7.5–8.5
Hardness (dGH)
✓ Compatible
Black Pacu
2–15
Scat (Brackish)
12–30
Water Type
✗ No overlap
Black Pacu
Freshwater Only
Scat (Brackish)
Brackish Required
Flow Preference
✓ Compatible
Black Pacu
Moderate
Scat (Brackish)
High
Min Tank Volume
Combined: 4560 L
Black Pacu
3800 L
Scat (Brackish)
450 L
Swimming Level
Shared: 2 zones
Black Pacu
MiddleBottom
Scat (Brackish)
MiddleBottom
🏷️Behavior Tags
Black Pacu
Plant DestroyerHyperactive / Fast SwimmerJumper (Lid Required)Aggressive Eater (Starves shy fish)Fry Predator
Scat (Brackish)
Plant DestroyerHyperactive / Fast SwimmerAggressive Eater (Starves shy fish)Fin Nipper

Behaviour & Temperament

Both Black Pacu and Scat (Brackish) are generally mild-mannered species with an aggression score of 4/10. Their matching temperaments mean neither fish is likely to dominate the other in a shared aquarium.

Black Pacu and Scat (Brackish) both frequent the Middle (Open Water) and 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: Black Pacu is a known jumper, so a tight-fitting lid is essential.

Water Parameters

The safe temperature window for both species falls between 22°C and 28°C. Aim for the midpoint of this range (around 25.0°C) for optimal comfort.

Both fish can tolerate a pH between 7.5 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 12–15 dGH. Regular testing will ensure conditions stay within this range.

Crucially, these species require different water types — one needs freshwater while the other requires brackish conditions. This is a hard barrier to keeping them together.

Tank Setup

To house Black Pacu and Scat (Brackish) together, plan for an aquarium of at least 4560 litres with a minimum length of 300 cm. This accounts for the larger species' space requirements with an additional 20 % buffer to reduce territorial tension.

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), Driftwood (Digestion/Hiding), Sand (Sifters), 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 Black Pacu and Scat (Brackish) live together?

No. This combination is not recommended. Key incompatibilities — such as different water type needs — make cohabitation unsafe.

What size tank do Black Pacu and Scat (Brackish) need?

A minimum of 4560 litres (tank length at least 300 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 Black Pacu and Scat (Brackish) together?

Keep the aquarium between 22°C and 28°C. A target of around 25.0°C sits comfortably within both species' preferred ranges.

Are Black Pacu or Scat (Brackish) aggressive?

Black Pacu is generally mild-mannered (4/10) and Scat (Brackish) is generally mild-mannered (4/10). Their similar temperaments generally lead to a peaceful coexistence.

What pH do Black Pacu and Scat (Brackish) need?

Both species overlap in the 7.5–7.5 pH range. Consistency is key — avoid sudden swings, and test regularly to stay within this window.

Will Scat (Brackish) nip Black Pacu's fins?

Scat (Brackish) is a known fin nipper. If Black Pacu has long or flowing fins, there is a real risk of fin damage. Keeping Scat (Brackish) in a larger group can help redirect nipping behaviour toward conspecifics.


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