Can Marbled Hatchetfish and Sunset Hap Live Together?
Marbled Hatchetfish and Sunset Hap are not recommended as tank mates due to conflicting pH requirements. Housing these species together is likely to result in stress, health problems, or direct harm to one or both fish.
At a Glance
Can your tank handle Marbled Hatchetfish and Sunset Hap?
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.
Behaviour & Temperament
Marbled Hatchetfish is a peaceful species (1/10), while Sunset Hap is moderately assertive (6/10). This notable difference means Sunset Hap may occasionally assert dominance over Marbled Hatchetfish.
In terms of spatial distribution, Marbled Hatchetfish prefers the Top (Surface) zone, whereas Sunset Hap 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: Marbled Hatchetfish 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 28°C. Aim for the midpoint of this range (around 26.0°C) for optimal comfort.
The pH requirements of Marbled Hatchetfish (5.5–7.5) and Sunset Hap (7.6–8.6) do not overlap, making it impossible to satisfy both species simultaneously.
For general hardness, the shared comfort zone is 10–12 dGH. Regular testing will ensure conditions stay within this range.
Tank Setup
To house Marbled Hatchetfish and Sunset Hap together, plan for an aquarium of at least 400 litres with a minimum length of 150 cm. This recommendation combines the stricter species minimums with a community-load allowance so the pairing has realistic long-term space and filtration headroom.
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, Leaf Litter/Blackwater, Sand (Sifters), 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.
Why This Pairing Usually Fails in Practice
Marbled Hatchetfish and Sunset Hap are the kind of pair that can look acceptable in a shop but become a maintenance problem at home. The main risk is not a single number in the chart; it is the way incompatible behavior, water needs, or pressure on space compounds over time once both fish are established in the same tank.
Suitable Tank Sizes
Standard aquarium sizes large enough for both Marbled Hatchetfish and Sunset Hap.
Frequently Asked Questions
Can Marbled Hatchetfish and Sunset Hap live together?
No. This combination is not recommended. Key incompatibilities — such as critical behavioural conflicts — make cohabitation unsafe.
What size tank do Marbled Hatchetfish and Sunset Hap need?
A minimum of 400 litres (tank length at least 150 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 Marbled Hatchetfish and Sunset Hap together?
Keep the aquarium between 24°C and 28°C. A target of around 26.0°C sits comfortably within both species' preferred ranges.
Are Marbled Hatchetfish or Sunset Hap aggressive?
Marbled Hatchetfish is peaceful (1/10) and Sunset Hap 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 Marbled Hatchetfish and Sunset Hap need?
Their pH requirements do not overlap. Marbled Hatchetfish prefers 5.5–7.5, while Sunset Hap needs 7.6–8.6. This makes them incompatible in the same water chemistry.
How do I manage Sunset Hap's territorial behaviour?
Provide line-of-sight breaks using rocks, driftwood, and dense planting. A larger tank gives Sunset Hap 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.
Shared setup supplies
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Guidarium Editorial Desk
Reviewed against Guidarium care, stocking, and compatibility standards. Read the editorial policy.
- Last reviewed
- May 4, 2026
- Last updated
- May 4, 2026
- Issues or corrections?
- Contact the editorial team
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