Rainbow emperor tetra
Nematobrycon lacortei
Also known as Rainbow tetra, Red-eyed emperor tetra, Lacorte's emperor tetra
FreshwaterFish
Care at a glance
- Temperature
- 73–81°F
- 23–27°C
- pH
- 6.0–7.5
- Adult size
- 2 in
- 5 cm
- Minimum tank
- 20 gal
- 75 L
- Temperament
- Mostly peaceful
- Social behavior
- Schooling
- Swim level
- Middle
- Difficulty
- Medium
- Breeding
- Medium
- Rarity
- Rare
- Family
- Characidae
- Origin
- Found in the Rio San Juan drainage of western Colombia.
Overview
Keep a group of 6 or more, ideally with a couple more females than males, since dominant males set up small territories and spar with each other. The color is best over dark substrate in soft, gently flowing water. They are peaceful toward other fish, and the fin display is worth giving them room to show off.
In the wild
Comes from clear and slightly tannin stained forest streams in western Colombia. These are gentle, shaded waters with sandy bottoms, leaf litter, and plenty of submerged wood and roots. The fish keep to the middle water in loose groups.
Good to know
Nematobrycon lacortei is closely related to the more familiar emperor tetra, but it is set apart by its bright red eye and rainbow sheen. Males grow long central tail rays and flowing fin extensions. It reaches about 5 cm.
Did you know
Males glow with green, blue, and gold and stare out through a striking ruby red eye, which is the quickest way to tell this species from the common emperor tetra.
Weekly picks
Tank mates
Rainbow emperor tetra is a mostly peaceful, schooling species that keeps to the middle. These picks share a community profile with it, are safe together in both directions, and overlap on water type, temperature and pH.

Marble wood shrimp
Atya scabra
Freshwater3.9 in (10 cm) · 20 gal (75 L)73–82°F (23–28°C)
Borneo kuhli loach
Pangio borneensis
Freshwater2.5 in (6.3 cm) · 20 gal (75 L)72–81°F (22–27°C)
Six-barred panchax
Epiplatys sexfasciatus
Freshwater3.9 in (10 cm) · 20 gal (75 L)72–81°F (22–27°C)
Humpbacked limia
Limia nigrofasciata
Freshwater2.4 in (6 cm) · 20 gal (75 L)72–82°F (22–28°C)
Bethan's cory
Brochis bethanae
Freshwater2.6 in (6.5 cm) · 20 gal (75 L)73–81°F (23–27°C)
Blue panchax
Aplocheilus panchax
Freshwater3.5 in (9 cm) · 20 gal (75 L)72–82°F (22–28°C)
Common questions
What size tank does a Rainbow emperor tetra need?
A Rainbow emperor tetra needs at least 20 gal (75 L). It spends most of its time in the middle.
What temperature and pH does a Rainbow emperor tetra need?
A Rainbow emperor tetra is comfortable at 73–81°F (23–27°C) with a pH of 6.0–7.5.
How big does a Rainbow emperor tetra get?
An adult Rainbow emperor tetra reaches about 2 in (5 cm).
Does a Rainbow emperor tetra need a group?
Yes. A Rainbow emperor tetra is a schooling species and should be kept in a group, not singly.
Related species
2 in (5 cm)20 gal (75 L)73–81°F (23–27°C)Emperor tetra
Nematobrycon palmeri
2 in (5 cm) · 20 gal (75 L)
2 in (5 cm)22 gal (85 L)72–79°F (22–26°C)Blue tetra
Knodus borki
2 in (5 cm) · 22 gal (85 L)
2 in (5 cm)18 gal (70 L)75–82°F (24–28°C)Glass tetra
Moenkhausia oligolepis
2 in (5 cm) · 18 gal (70 L)
2 in (5 cm)20 gal (75 L)72–79°F (22–26°C)Green fire tetra
Aphyocharax rathbuni
2 in (5 cm) · 20 gal (75 L)
2.2 in (5.5 cm)20 gal (75 L)72–82°F (22–28°C)Bloodfin tetra
Aphyocharax anisitsi
2.2 in (5.5 cm) · 20 gal (75 L)
2.4 in (6 cm)20 gal (75 L)68–79°F (20–26°C)Black widow tetra
Gymnocorymbus ternetzi
2.4 in (6 cm) · 20 gal (75 L)
