Can Ajamaru Rainbowfish and Cairns Rainbowfish Live Together?

Possible with Caution

Keeping Ajamaru Rainbowfish and Cairns Rainbowfish together is possible but requires caution, though some care is needed. Provide a spacious tank of at least 150 litres with plenty of hiding spots to reduce stress. Monitor behaviour closely, especially during the first few weeks.


At a Glance

Ajamaru Rainbowfish

Melanotaenia ajamaruensis

Cairns Rainbowfish

Cairnsichthys rhombosomoides

🐟Family Group
Ajamaru Rainbowfish
Rainbowfish
Cairns Rainbowfish
Rainbowfish
Temperament
Ajamaru Rainbowfish
Peaceful (2/10)
Cairns Rainbowfish
Peaceful (2/10)
Temperature
✓ Compatible
Ajamaru Rainbowfish
24–28°C
Cairns Rainbowfish
20–26°C
pH Range
✓ Compatible
Ajamaru Rainbowfish
7.2–8.5
Cairns Rainbowfish
6.5–7.6
Hardness (dGH)
✓ Compatible
Ajamaru Rainbowfish
8–20
Cairns Rainbowfish
2–10
Water Type
✓ Compatible
Ajamaru Rainbowfish
Freshwater Only
Cairns Rainbowfish
Freshwater Only
Flow Preference
✓ Compatible
Ajamaru Rainbowfish
Moderate
Cairns Rainbowfish
High
Min Tank Volume
Combined: 150 L
Ajamaru Rainbowfish
150 L
Cairns Rainbowfish
110 L
Swimming Level
Shared: 2 zones
Ajamaru Rainbowfish
TopMiddle
Cairns Rainbowfish
MiddleTop
🏷️Behavior Tags
Ajamaru Rainbowfish
Hyperactive / Fast SwimmerJumper (Lid Required)Fry Predator
Cairns Rainbowfish
Hyperactive / Fast SwimmerJumper (Lid Required)Fry Predator
Stocking calculator

Can your tank handle Ajamaru Rainbowfish and Cairns Rainbowfish?

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.

Ajamaru Rainbowfish
Cairns Rainbowfish
Test both in my tank

Behaviour & Temperament

Both Ajamaru Rainbowfish and Cairns Rainbowfish are peaceful species with an aggression score of 2/10. Their matching temperaments mean neither fish is likely to dominate the other in a shared aquarium.

Ajamaru Rainbowfish and Cairns Rainbowfish 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: Ajamaru Rainbowfish 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 26°C. Aim for the midpoint of this range (around 25.0°C) for optimal comfort.

Both fish can tolerate a pH between 7.2 and 7.6. Maintaining a stable value within this band is more important than hitting an exact number.

For general hardness, the shared comfort zone is 8–10 dGH. Regular testing will ensure conditions stay within this range.

Tank Setup

To house Ajamaru Rainbowfish and Cairns Rainbowfish together, plan for an aquarium of at least 150 litres with a minimum length of 90 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: Plants - Densely covered, Smooth Gravel (Sensitive Barbels), Driftwood (Digestion/Hiding), Leaf Litter/Blackwater. 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.

Suitable Tank Sizes

Standard aquarium sizes large enough for both Ajamaru Rainbowfish and Cairns Rainbowfish.

Show 9 more tank sizes

Frequently Asked Questions

Can Ajamaru Rainbowfish and Cairns Rainbowfish live together?

They can coexist, but the pairing requires careful monitoring. Provide ample space (at least 150 litres), plenty of hiding spots, and watch for signs of stress or aggression.

What size tank do Ajamaru Rainbowfish and Cairns Rainbowfish need?

A minimum of 150 litres (tank length at least 90 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 Ajamaru Rainbowfish and Cairns Rainbowfish together?

Keep the aquarium between 24°C and 26°C. A target of around 25.0°C sits comfortably within both species' preferred ranges.

Are Ajamaru Rainbowfish or Cairns Rainbowfish aggressive?

Ajamaru Rainbowfish is peaceful (2/10) and Cairns Rainbowfish is peaceful (2/10). Their similar temperaments generally lead to a peaceful coexistence.

What pH do Ajamaru Rainbowfish and Cairns Rainbowfish need?

Both species overlap in the 7.2–7.6 pH range. Consistency is key — avoid sudden swings, and test regularly to stay within this window.


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