Can Blue Tetra and Electric Blue Johannii Live Together?
Blue Tetra and Electric Blue Johannii 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 Blue Tetra and Electric Blue Johannii?
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
Blue Tetra is a moderately assertive species (5/10), while Electric Blue Johannii is semi-aggressive (8/10). This modest difference means Electric Blue Johannii may occasionally assert dominance over Blue Tetra.
Blue Tetra and Electric Blue Johannii 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.
Worth noting: Blue Tetra 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 26°C. Aim for the midpoint of this range (around 25.0°C) for optimal comfort.
The pH requirements of Blue Tetra (5.5–7.5) and Electric Blue Johannii (7.8–8.6) 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 Blue Tetra and Electric Blue Johannii together, plan for an aquarium of at least 203 litres with a minimum length of 90 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 - Densely covered, Sand (Sifters), Established Algae (Otocinclus). Meeting these requirements will help both species thrive.
Note a potential conflict in setup requirements: Electric Blue Johannii is a plant destroyer, which conflicts with Blue Tetra's requirement for live plants. Compromise where possible or prioritise the more critical need.
Both species do well with moderate (standard) water movement, so a standard filtration setup rated for the tank volume should suffice.
Why This Pairing Usually Fails in Practice
Blue Tetra and Electric Blue Johannii 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 Blue Tetra and Electric Blue Johannii.
55 Gallon Standard
60 Gallon Breeder
75 Gallon Standard
90 Gallon Standard
125 Gallon Standard
150 Gallon High
Frequently Asked Questions
Can Blue Tetra and Electric Blue Johannii live together?
No. This combination is not recommended. Key incompatibilities — such as critical behavioural conflicts — make cohabitation unsafe.
What size tank do Blue Tetra and Electric Blue Johannii need?
A minimum of 203 litres (tank length at least 90 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 Tetra and Electric Blue Johannii together?
Keep the aquarium between 24°C and 26°C. A target of around 25.0°C sits comfortably within both species' preferred ranges.
Are Blue Tetra or Electric Blue Johannii aggressive?
Blue Tetra is moderately assertive (5/10) and Electric Blue Johannii is semi-aggressive (8/10). Their similar temperaments generally lead to a peaceful coexistence.
What pH do Blue Tetra and Electric Blue Johannii need?
Their pH requirements do not overlap. Blue Tetra prefers 5.5–7.5, while Electric Blue Johannii needs 7.8–8.6. This makes them incompatible in the same water chemistry.
Will Blue Tetra nip Electric Blue Johannii's fins?
Blue Tetra is a known fin nipper. If Electric Blue Johannii has long or flowing fins, there is a real risk of fin damage. Keeping Blue Tetra in a larger group can help redirect nipping behaviour toward conspecifics.
How do I manage Electric Blue Johannii's territorial behaviour?
Provide line-of-sight breaks using rocks, driftwood, and dense planting. A larger tank gives Electric Blue Johannii 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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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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