Blue betta (Betta smaragdina)

Family: Osphronemidae

A semi-aggressive carnivore osphronemidae from the Mekong basin of Southeast Asia (Thailand, Cambodia and Laos) — beginner-friendly.

Care parameters

Water temperature: 24–27 °C
pH: 6–8
GH hardness: 5–19 dGH
Adult length: 4.9–7 cm
Minimum tank: 70 L
Water layer: Upper; surface-oriented
Difficulty: Easy
Temperament: Semi-aggressive; one male per tank
Origin: 东南亚湄公河流域（泰国、柬埔寨、老挝）

Species overview

Betta smaragdina is a Osphronemidae. In the aquarium it stays semi-aggressive. Plan on 4.9–7 cm of adult fish at 24–27 °C. Related profiles: Betta imbellis, Betta splendens, Betta albimarginata.

Native biotope

Habitat: Clear streams, rivers and still waters
Flow: Still to very gentle water
Dissolved O₂: Tolerates low oxygen

Aquascape & hardware

Substrate: Smooth gravel and sand with open floor space
Hardscape: Driftwood, water-worn stones and shelters that mimic the native biotope
Plants: Hardy plants on hardscape; keep the floor open

Temperament, diet & tankmates

Schooling: Solitary, pairs or small groups
Diet: Carnivore; quality prepared foods with variety; regular frozen or live foods
Recommended tankmates: Amur False Gudgeon — Similar size and water needs
Striped Bitterling — Similar size and water needs
Acheilognathus gracilis — Similar size and water needs
Avoid keeping with: Its own males — Territorial fighting
Long-finned fish — Prone to fin nipping
Fin-nipping species — Its fins become targets

Breeding & notes

Sexual dimorphism: Males are typically slimmer and more intensely colored; females fuller-bodied
Breeding method: Bubble nester; condition with rich foods and simulate seasonal changes

Frequently asked questions

Is Blue betta easy to keep?

Beginner-friendly. Semi-aggressive; one male per tank; solitary, pairs or small groups.

What temperature and water chemistry does Blue betta need?

Set the heater to 24–27 °C and avoid swings. pH 6–8, GH 5–19 dGH suit it.

How big does Blue betta get, and what tank size?

Adults reach 4.9–7 cm; it is upper; surface-oriented. Plan for at least 70 litres.

What does Blue betta eat?

Carnivore; quality prepared foods with variety; regular frozen or live foods. Feed two small meals a day rather than one large one.

Can Blue betta live with other fish?

Yes, with care. Semi-aggressive; one male per tank — pair it with Amur False Gudgeon — Similar size and water needs, Striped Bitterling — Similar size and water needs, Acheilognathus gracilis — Similar size and water needs and skip Its own males — Territorial fighting, Long-finned fish — Prone to fin nipping, Fin-nipping species — Its fins become targets.

Where does Blue betta come from?

Comes from 东南亚湄公河流域（泰国、柬埔寨、老挝）: clear streams, rivers and still waters. Expect still to very gentle water and tolerates low oxygen.

Does Blue betta jump?

A confirmed jumper: fit a tight lid and lower the waterline slightly.

How does Blue betta breed?

In the aquarium: bubble nester; condition with rich foods and simulate seasonal changes. Males are typically slimmer and more intensely colored; females fuller-bodied.