Can Clown Killifish and Knight Goby Live Together?
Clown Killifish and Knight Goby are not recommended as tank mates due to 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 Knight Goby is moderately assertive (6/10). This notable difference means Knight Goby may occasionally assert dominance over Clown Killifish.
In terms of spatial distribution, Clown Killifish prefers the Top (Surface) zone, whereas Knight Goby 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: Shrimp eaters may also prey on very small nano fish.
Worth noting: Clown Killifish is a known jumper, so a tight-fitting lid is essential.
Water Parameters
The safe temperature window for both species falls between 23°C and 27°C. Aim for the midpoint of this range (around 25.0°C) for optimal comfort.
Both fish can tolerate a pH between 7 and 7. Maintaining a stable value within this band is more important than hitting an exact number.
Hardness requirements are incompatible: Clown Killifish needs 1–8 dGH while Knight Goby requires 10–30 dGH. An aquarium test kit is recommended for monitoring.
Tank Setup
To house Clown Killifish and Knight Goby together, plan for an aquarium of at least 90 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.
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), Shells (Breeding/Hiding), 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.
Diet & Feeding
Feeding time deserves special attention with this pairing. Knight Goby is a known shrimp eater and may prey on small invertebrates or nano fish like Clown Killifish.
Frequently Asked Questions
Can Clown Killifish and Knight Goby 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 Knight Goby need?▾
A minimum of 90 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 Clown Killifish and Knight Goby together?▾
Keep the aquarium between 23°C and 27°C. A target of around 25.0°C sits comfortably within both species' preferred ranges.
Are Clown Killifish or Knight Goby aggressive?▾
Clown Killifish is peaceful (2/10) and Knight Goby is moderately assertive (6/10). The gap in aggression levels means the calmer fish may experience stress from the more assertive one.
What pH do Clown Killifish and Knight Goby need?▾
Both species overlap in the 7–7 pH range. Consistency is key — avoid sudden swings, and test regularly to stay within this window.
Will Knight Goby nip Clown Killifish's fins?▾
Knight Goby is a known fin nipper. If Clown Killifish has long or flowing fins, there is a real risk of fin damage. Keeping Knight Goby in a larger group can help redirect nipping behaviour toward conspecifics.
How do I manage Knight Goby's territorial behaviour?▾
Provide line-of-sight breaks using rocks, driftwood, and dense planting. A larger tank gives Knight Goby space to claim a territory without encroaching on the other fish's area. Adding décor that divides the tank into distinct zones works especially well.
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