Can Clown Killifish and Cuckoo Catfish Live Together?
Clown Killifish and Cuckoo Catfish are not recommended as tank mates due to conflicting pH requirements and incompatible hardness ranges. Housing these species together is likely to result in stress, health problems, or direct harm to one or both fish.
At a Glance
Behaviour & Temperament
Clown Killifish is a peaceful species (2/10), while Cuckoo Catfish is moderately assertive (5/10). This modest difference means Cuckoo Catfish may occasionally assert dominance over Clown Killifish.
In terms of spatial distribution, Clown Killifish prefers the Top (Surface) zone, whereas Cuckoo Catfish occupies the Middle (Open Water) and Bottom (Substrate) zones. 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: Cuckoo Catfish is nocturnal and will be most active after lights-out, naturally reducing daytime encounters. Also, Clown Killifish 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 27°C. Aim for the midpoint of this range (around 25.5°C) for optimal comfort.
The pH requirements of Clown Killifish (5–7) and Cuckoo Catfish (7.5–9) do not overlap, making it impossible to satisfy both species simultaneously.
Hardness requirements are incompatible: Clown Killifish needs 1–8 dGH while Cuckoo Catfish requires 10–25 dGH. An aquarium test kit is recommended for monitoring.
Tank Setup
To house Clown Killifish and Cuckoo Catfish together, plan for an aquarium of at least 408 litres with a minimum length of 120 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 - Floating, Plants - Densely covered, Leaf Litter/Blackwater, Sand (Sifters), Smooth Gravel (Sensitive Barbels), Driftwood (Digestion/Hiding). 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.
Find the right tank equipment
Browse tanks, décor, and equipment suited for this setup.
Frequently Asked Questions
Can Clown Killifish and Cuckoo Catfish live together?▾
No. This combination is not recommended. Key incompatibilities — such as critical behavioural conflicts — make cohabitation unsafe.
What size tank do Clown Killifish and Cuckoo Catfish need?▾
A minimum of 408 litres (tank length at least 120 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 Clown Killifish and Cuckoo Catfish 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 Clown Killifish or Cuckoo Catfish aggressive?▾
Clown Killifish is peaceful (2/10) and Cuckoo Catfish is moderately assertive (5/10). Their similar temperaments generally lead to a peaceful coexistence.
What pH do Clown Killifish and Cuckoo Catfish need?▾
Their pH requirements do not overlap. Clown Killifish prefers 5–7, while Cuckoo Catfish needs 7.5–9. This makes them incompatible in the same water chemistry.
Does Cuckoo Catfish being nocturnal affect compatibility?▾
Cuckoo Catfish is most active after lights-out, which naturally reduces daytime encounters with its tank mate. This can actually be beneficial, as both fish get undisturbed time to feed and explore. Just ensure food reaches Cuckoo Catfish during evening hours.
Related Comparisons
Clown Killifish & Gardner's Killifish
·
Clown Killifish & Japanese Ricefish (Medaka)
·
Clown Killifish & Norman's Lampeye Killifish
·
Clown Killifish & Rachov's Killifish (Annual)
·
Clown Killifish & Amazon Leaf Fish
·
Clown Killifish & Apple Snail
·
Cuckoo Catfish & Featherfin Squeaker
·
Cuckoo Catfish & Pictus Catfish
·
Cuckoo Catfish & Clown Pleco (L104)
·
Cuckoo Catfish & Common Pleco
·
Cuckoo Catfish & Iridescent Shark
·
Cuckoo Catfish & Red-Tail Catfish
·