Can Arapaima and Cuban Gar Live Together?

Possible with Caution

Keeping Arapaima and Cuban Gar together is possible but requires caution, though some care is needed. Provide a spacious tank of at least 15000 litres with plenty of hiding spots to reduce stress. Monitor behaviour closely, especially during the first few weeks.


At a Glance

Arapaima

Arapaima gigas

Cuban Gar

Atractosteus tristoechus

🐟Family Group
Arapaima
Oddballs
Cuban Gar
Oddballs
Temperament
Arapaima
Aggressive (7/10)
Cuban Gar
Semi-Aggressive (6/10)
Temperature
βœ“ Compatible
Arapaima
24–30Β°C
Cuban Gar
22–30Β°C
pH Range
βœ“ Compatible
Arapaima
6–7.5
Cuban Gar
6.5–8
Hardness (dGH)
βœ“ Compatible
Arapaima
2–15
Cuban Gar
8–20
Water Type
βœ“ Compatible
Arapaima
Freshwater Only
Cuban Gar
Brackish Tolerant
Flow Preference
βœ“ Compatible
Arapaima
Low
Cuban Gar
Moderate
Min Tank Volume
Combined: 15000 L
Arapaima
15000 L
Cuban Gar
3785 L
Swimming Level
Shared: 2 zones
Arapaima
TopMiddle
Cuban Gar
TopMiddle
🏷️Behavior Tags
Arapaima
Piscivore (Eats small/nano fish)Jumper (Lid Required)Hyperactive / Fast SwimmerPlant DestroyerAggressive to same species/look-alikes
Cuban Gar
Piscivore (Eats small/nano fish)Jumper (Lid Required)
Stocking calculator

Can your tank handle Arapaima and Cuban Gar?

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.

Arapaima
Cuban Gar
Test both in my tank

Behaviour & Temperament

Arapaima is a semi-aggressive species (7/10), while Cuban Gar is moderately assertive (6/10). This modest difference means Arapaima may occasionally assert dominance over Cuban Gar.

Arapaima and Cuban Gar both frequent the Top (Surface) and 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: Arapaima is a known jumper, so a tight-fitting lid is essential.

Water Parameters

The safe temperature window for both species falls between 24Β°C and 30Β°C. Aim for the midpoint of this range (around 27.0Β°C) for optimal comfort.

Both fish can tolerate a pH between 6.5 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 8–15 dGH. Regular testing will ensure conditions stay within this range.

Tank Setup

To house Arapaima and Cuban Gar together, plan for an aquarium of at least 15000 litres with a minimum length of 600 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 β€” caves, driftwood, and dense plant clusters β€” so the less dominant fish can retreat when needed.

Specific environmental needs for this combination include: 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.

Frequently Asked Questions

Can Arapaima and Cuban Gar live together?

They can coexist, but the pairing requires careful monitoring. Provide ample space (at least 15000 litres), plenty of hiding spots, and watch for signs of stress or aggression.

What size tank do Arapaima and Cuban Gar need?

A minimum of 15000 litres (tank length at least 600 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 Arapaima and Cuban Gar together?

Keep the aquarium between 24Β°C and 30Β°C. A target of around 27.0Β°C sits comfortably within both species' preferred ranges.

Are Arapaima or Cuban Gar aggressive?

Arapaima is semi-aggressive (7/10) and Cuban Gar is moderately assertive (6/10). Their similar temperaments generally lead to a peaceful coexistence.

What pH do Arapaima and Cuban Gar need?

Both species overlap in the 6.5–7.5 pH range. Consistency is key β€” avoid sudden swings, and test regularly to stay within this window.


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