Can Betta Smaragdina and Blue Back Blue Eye Live Together?
Betta Smaragdina and Blue Back Blue Eye are not recommended as tank mates due to incompatible water types. 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 Betta Smaragdina and Blue Back Blue Eye?
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
Betta Smaragdina is a moderately assertive species (5/10), while Blue Back Blue Eye is peaceful (2/10). This modest difference means Betta Smaragdina may occasionally assert dominance over Blue Back Blue Eye.
Betta Smaragdina and Blue Back Blue Eye both frequent the Top (Surface) and 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: Shrimp eaters may also prey on very small nano fish.
Worth noting: Betta Smaragdina is a known jumper, so a tight-fitting lid is essential.
Water Parameters
The safe temperature window for both species falls between 22°C and 28°C. Aim for the midpoint of this range (around 25.0°C) for optimal comfort.
Both fish can tolerate a pH between 7 and 7.5. Maintaining a stable value within this band is more important than hitting an exact number.
For general hardness, the shared comfort zone is 10–12 dGH. Regular testing will ensure conditions stay within this range.
Crucially, these species require different water types — one needs freshwater while the other requires brackish conditions. This is a hard barrier to keeping them together.
Tank Setup
To house Betta Smaragdina and Blue Back Blue Eye together, plan for an aquarium of at least 38 litres with a minimum length of 45 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, Plants - Floating, Leaf Litter/Blackwater, Driftwood (Digestion/Hiding), Sand (Sifters). 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
Betta Smaragdina and Blue Back Blue Eye 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 Betta Smaragdina and Blue Back Blue Eye.
10 Gallon Standard
15 Gallon Standard
20 Gallon High
20 Gallon Long
29 Gallon Standard
30 Gallon Breeder
Show 22 more tank sizes
Diet & Feeding
Feeding time deserves special attention with this pairing. Betta Smaragdina is a known shrimp eater and may prey on small invertebrates or nano fish like Blue Back Blue Eye.
Frequently Asked Questions
Can Betta Smaragdina and Blue Back Blue Eye live together?
No. This combination is not recommended. Key incompatibilities — such as different water type needs — make cohabitation unsafe.
What size tank do Betta Smaragdina and Blue Back Blue Eye need?
A minimum of 38 litres (tank length at least 45 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 Betta Smaragdina and Blue Back Blue Eye together?
Keep the aquarium between 22°C and 28°C. A target of around 25.0°C sits comfortably within both species' preferred ranges.
Are Betta Smaragdina or Blue Back Blue Eye aggressive?
Betta Smaragdina is moderately assertive (5/10) and Blue Back Blue Eye is peaceful (2/10). Their similar temperaments generally lead to a peaceful coexistence.
What pH do Betta Smaragdina and Blue Back Blue Eye need?
Both species overlap in the 7–7.5 pH range. Consistency is key — avoid sudden swings, and test regularly to stay within this window.
How do I manage Betta Smaragdina's territorial behaviour?
Provide line-of-sight breaks using rocks, driftwood, and dense planting. A larger tank gives Betta Smaragdina 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
We may earn from qualifying purchases
Guidarium Editorial Desk
Reviewed against Guidarium care, stocking, and compatibility standards. Read the editorial policy.
- Last reviewed
- May 2, 2026
- Last updated
- May 2, 2026
- Issues or corrections?
- Contact the editorial team
Related Comparisons
Betta Smaragdina & Banded Gourami
·
Betta Smaragdina & Betta Imbellis
·
Betta Smaragdina & Betta Macrostoma
·
Betta Smaragdina & Betta (Siamese Fighting Fish)
·
Betta Smaragdina & Dwarf Gourami
·
Betta Smaragdina & Kissing Gourami
·
Blue Back Blue Eye & Ajamaru Rainbowfish
·
Blue Back Blue Eye & Allen's Rainbowfish
·
Blue Back Blue Eye & Angfa Rainbowfish
·
Blue Back Blue Eye & Axelrod's Rainbowfish
·
Blue Back Blue Eye & Barred Rainbowfish
·
Blue Back Blue Eye & Batanta Rainbowfish
·