Can Forktail Blue-eye and Scat (Brackish) Live Together?

🔴Not Recommended

Forktail Blue-eye 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

Forktail Blue-eye

Pseudomugil furcatus

Scat (Brackish)

Scatophagus argus

🐠Family Group
Forktail Blue-eye
Rainbowfish
Scat (Brackish)
Oddballs
Temperament
Forktail Blue-eye
Peaceful (2/10)
Scat (Brackish)
Mostly Peaceful (4/10)
Temperature
✓ Compatible
Forktail Blue-eye
24–28°C
Scat (Brackish)
20–28°C
pH Range
✓ Compatible
Forktail Blue-eye
7–8
Scat (Brackish)
7.5–8.5
Hardness (dGH)
✓ Compatible
Forktail Blue-eye
5–15
Scat (Brackish)
12–30
Water Type
✗ No overlap
Forktail Blue-eye
Freshwater Only
Scat (Brackish)
Brackish Required
Flow Preference
✓ Compatible
Forktail Blue-eye
Moderate
Scat (Brackish)
High
Min Tank Volume
Combined: 540 L
Forktail Blue-eye
55 L
Scat (Brackish)
450 L
Swimming Level
Shared: 1 zone
Forktail Blue-eye
TopMiddle
Scat (Brackish)
MiddleBottom
🏷️Behavior Tags
Forktail Blue-eye
Nano / Bite-sized (Predation Risk)Hyperactive / Fast SwimmerJumper (Lid Required)
Scat (Brackish)
Plant DestroyerHyperactive / Fast SwimmerAggressive Eater (Starves shy fish)Fin Nipper

Behaviour & Temperament

Forktail Blue-eye is a peaceful species (2/10), while Scat (Brackish) is generally mild-mannered (4/10). This modest difference means Scat (Brackish) may occasionally assert dominance over Forktail Blue-eye.

Forktail Blue-eye and Scat (Brackish) both frequent the 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.

Worth noting: Forktail Blue-eye 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 28°C. Aim for the midpoint of this range (around 26.0°C) for optimal comfort.

Both fish can tolerate a pH between 7.5 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 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. An aquarium test kit is recommended for monitoring.

Tank Setup

To house Forktail Blue-eye and Scat (Brackish) together, plan for an aquarium of at least 540 litres with a minimum length of 150 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: Plants - Densely covered, Sand (Sifters), Smooth Gravel (Sensitive Barbels), Established Algae (Otocinclus). Meeting these requirements will help both species thrive.

Note a potential conflict in setup requirements: Scat (Brackish) is a plant destroyer, which conflicts with Forktail Blue-eye's requirement for live plants. Compromise where possible or prioritise the more critical need.

Both species do well with moderate (standard) water movement, so a standard filtration setup rated for the tank volume should suffice.

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Frequently Asked Questions

Can Forktail Blue-eye 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 Forktail Blue-eye and Scat (Brackish) need?

A minimum of 540 litres (tank length at least 150 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 Forktail Blue-eye and Scat (Brackish) together?

Keep the aquarium between 24°C and 28°C. A target of around 26.0°C sits comfortably within both species' preferred ranges.

Are Forktail Blue-eye or Scat (Brackish) aggressive?

Forktail Blue-eye is peaceful (2/10) and Scat (Brackish) is generally mild-mannered (4/10). Their similar temperaments generally lead to a peaceful coexistence.

What pH do Forktail Blue-eye and Scat (Brackish) need?

Both species overlap in the 7.5–8 pH range. Consistency is key — avoid sudden swings, and test regularly to stay within this window.

Will Scat (Brackish) nip Forktail Blue-eye's fins?

Scat (Brackish) is a known fin nipper. If Forktail Blue-eye 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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