Can Blue Dolphin (Hap) and Cardinal Tetra Live Together?
Blue Dolphin (Hap) and Cardinal Tetra 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
Blue Dolphin (Hap) is a moderately assertive species (5/10), while Cardinal Tetra is peaceful (1/10). This notable difference means Blue Dolphin (Hap) may occasionally assert dominance over Cardinal Tetra.
Blue Dolphin (Hap) and Cardinal Tetra both frequent the 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.
Additional behavioural considerations to keep in mind: Hyperactive swimmers can stress shy, slow-moving species through constant motion.
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 Blue Dolphin (Hap) (7.5–8.6) and Cardinal Tetra (4–7) do not overlap, making it impossible to satisfy both species simultaneously.
Hardness requirements are incompatible: Blue Dolphin (Hap) needs 10–25 dGH while Cardinal Tetra requires 1–8 dGH.
Tank Setup
To house Blue Dolphin (Hap) and Cardinal Tetra together, plan for an aquarium of at least 570 litres with a minimum length of 150 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: Sand (Sifters), Smooth Gravel (Sensitive Barbels), Leaf Litter/Blackwater, Driftwood (Digestion/Hiding), Plants - Densely covered. 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.
Frequently Asked Questions
Can Blue Dolphin (Hap) and Cardinal Tetra live together?▾
No. This combination is not recommended. Key incompatibilities — such as critical behavioural conflicts — make cohabitation unsafe.
What size tank do Blue Dolphin (Hap) and Cardinal Tetra need?▾
A minimum of 570 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 Blue Dolphin (Hap) and Cardinal Tetra 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 Blue Dolphin (Hap) or Cardinal Tetra aggressive?▾
Blue Dolphin (Hap) is moderately assertive (5/10) and Cardinal Tetra is peaceful (1/10). The gap in aggression levels means the calmer fish may experience stress from the more assertive one.
What pH do Blue Dolphin (Hap) and Cardinal Tetra need?▾
Their pH requirements do not overlap. Blue Dolphin (Hap) prefers 7.5–8.6, while Cardinal Tetra needs 4–7. This makes them incompatible in the same water chemistry.
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