Can Cardinal Tetra and Clown Killifish Live Together?

🟡Possible with Caution

Keeping Cardinal Tetra and Clown Killifish together is possible but requires caution due to potential behavioral clashes. Provide a spacious tank of at least 66 litres with plenty of hiding spots to reduce stress. Monitor behaviour closely, especially during the first few weeks.


At a Glance

Cardinal Tetra

Paracheirodon axelrodi

Clown Killifish

Epiplatys annulatus

🐠Family Group
Cardinal Tetra
Characins
Clown Killifish
Killifish
Temperament
Cardinal Tetra
Peaceful (1/10)
Clown Killifish
Peaceful (2/10)
Temperature
✓ Compatible
Cardinal Tetra
24–29°C
Clown Killifish
23–27°C
pH Range
✓ Compatible
Cardinal Tetra
4–7
Clown Killifish
5–7
Hardness (dGH)
✓ Compatible
Cardinal Tetra
1–8
Clown Killifish
1–8
Water Type
✓ Compatible
Cardinal Tetra
Freshwater Only
Clown Killifish
Freshwater Only
Flow Preference
✓ Compatible
Cardinal Tetra
Low
Clown Killifish
Low
Min Tank Volume
Combined: 66 L
Cardinal Tetra
55 L
Clown Killifish
19 L
Swimming Level
✓ Different zones
Cardinal Tetra
Middle
Clown Killifish
Top
🏷️Behavior Tags
Cardinal Tetra
Nano / Bite-sized (Predation Risk)Hyperactive / Fast SwimmerShy / Slow Moving (Easily Stressed)
Clown Killifish
Nano / Bite-sized (Predation Risk)Jumper (Lid Required)Shy / Slow Moving (Easily Stressed)Fry Predator

Behaviour & Temperament

Cardinal Tetra is a peaceful species (1/10), while Clown Killifish is peaceful (2/10). This modest difference means Clown Killifish may occasionally assert dominance over Cardinal Tetra.

In terms of spatial distribution, Cardinal Tetra prefers the Middle (Open Water) zone, whereas Clown Killifish occupies the Top (Surface) zone. Because they use different levels of the water column, territorial disputes are less likely and the tank will appear more balanced.

Additional behavioural considerations to keep in mind: Hyperactive swimmers can stress shy, slow-moving species through constant motion.

Worth noting: Clown Killifish is a known jumper, so a tight-fitting lid is essential.

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.

Water Parameters

The safe temperature window for both species falls between 24°C and 27°C. Aim for the midpoint of this range (around 25.5°C) for optimal comfort.

Both fish can tolerate a pH between 5 and 7. Maintaining a stable value within this band is more important than hitting an exact number.

For general hardness, the shared comfort zone is 1–8 dGH. Regular testing will ensure conditions stay within this range.

Tank Setup

To house Cardinal Tetra and Clown Killifish together, plan for an aquarium of at least 66 litres with a minimum length of 60 cm. This accounts for the larger species' space requirements with an additional 20 % buffer to reduce territorial tension.

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: Leaf Litter/Blackwater, Driftwood (Digestion/Hiding), Plants - Densely covered, Plants - Floating. 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 Cardinal Tetra and Clown Killifish live together?

They can coexist, but the pairing requires careful monitoring. Provide ample space (at least 66 litres), plenty of hiding spots, and watch for signs of stress or aggression.

What size tank do Cardinal Tetra and Clown Killifish need?

A minimum of 66 litres (tank length at least 60 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 Cardinal Tetra and Clown Killifish together?

Keep the aquarium between 24°C and 27°C. A target of around 25.5°C sits comfortably within both species' preferred ranges.

Are Cardinal Tetra or Clown Killifish aggressive?

Cardinal Tetra is peaceful (1/10) and Clown Killifish is peaceful (2/10). Their similar temperaments generally lead to a peaceful coexistence.

What pH do Cardinal Tetra and Clown Killifish need?

Both species overlap in the 5–7 pH range. Consistency is key — avoid sudden swings, and test regularly to stay within this window.


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