Turquoise Rainbowfish

Melanotaenia lacustris

Also sold as Lake Kutubu rainbowfish

Synonyms Blue rainbowfish

Turquoise Rainbowfish (Melanotaenia lacustris) is a peaceful freshwater fish that reaches about 12 cm (4.7 in) and swims in open water in a shoal. It wants 68–77°F (20–25°C) and pH 7–9, is kept in groups of 6 or more, and needs a tank of at least 108 L (29 gal).

At a glance

Type	Fish
Adult size	12 cm (4.7 in)
Minimum tank	108 L (29 gal)
Group size	6 or more
Temperature	68–77°F (20–25°C)
pH	7–9
Temperament	Peaceful
Lifespan	5–8 years
Eats shrimp	Yes

Before it goes in

Turquoise Rainbowfish needs at least 108 L (29 gal). The smallest size in this library that clears that is the 29 Gallon.
Keep 6 or more. Below that it hides, colours down and is far more likely to be picked on.
It eats shrimp. Cherry Shrimp, Crystal Red Shrimp and Bamboo Shrimp are on the menu.
It is the wrong size to share a tank with Iridescent Shark, Senegal Bichir and Black Ghost Knifefish: it ends up as food.
It holds at 68–77°F (20–25°C). That shares a window with Betta and Cherry Shrimp, but not with German Blue Ram and Discus.
A group of 6 takes up roughly 131% of what a 29 Gallon will comfortably hold, so plan the rest of the stock around it.

What tank size does it need?

At least 108 L (29 gal). The smallest size here that clears it is the 29 Gallon.

How many should I keep?

6 or more. Fewer than that and it spends its time hiding instead of out in the open.

Will it eat shrimp?

Yes. Shrimp are food to it, so pick one or the other.

What water does it want?

68–77°F (20–25°C), pH 7–9.

How long does it live?

5–8 years in a tank that suits it. That is how long you are signing up for.

Good tank mates

Tank mates from this library that share its temperature window, are peaceful and eat neither it nor its young: Goldfish, Bristlenose Pleco, Celestial Pearl Danio, Molly and Otocinclus.
Plants that hold up with it: Hygrophila corymbosa 'Siamensis', Water Sprite, Anubias nana 'Petite' and Cryptocoryne wendtii.

Often compared with

	Turquoise Rainbowfish	Boesemani Rainbowfish	Dwarf Neon Rainbowfish
Adult size	12 cm	12 cm	6 cm
Min tank	108 L	200 L	80 L
Group	6+	6+	6+
Temperature	68–77°F (20–25°C)	75–82°F (24–28°C)	73–82°F (23–28°C)
Eats shrimp	Yes	Yes	Yes

More livestock

Plan a tank with Turquoise Rainbowfish →

Sources (3) · checked Sep 2026