Blue tetra
Knodus borki
FreshwaterFish
Care at a glance
- Temperature
- 72–79°F
- 22–26°C
- pH
- 5.5–7.0
- Adult size
- 2 in
- 5 cm
- Minimum tank
- 22 gal
- 85 L
- Temperament
- Mostly peaceful
- Social behavior
- Schooling
- Swim level
- Middle
- Difficulty
- Medium
- Breeding
- Egg scatterer
- Rarity
- Common
- Family
- Characidae
- Origin
- Colombia, Brazil
Overview
The blue tetra is a mostly peaceful schooling fish for a soft-water community tank. It is a step up from the easiest fish.
Did you know
The blue tetra belongs to Knodus, a confusing genus. Fish sold as blue tetras often turn out to be several different species mixed together. Knodus borki was only described in 2008, so a lot of older aquarium information under that common name refers to other fish.
Caring for the blue tetra
Give a group of blue tetras 22 gal (85 L) or more, so they have room to school. Aim for a dim, soft setup with subdued lighting, some plants and tannin-stained water if you can manage it. Keep the water at 72 to 79°F (22 to 26°C), with a pH of 5.5 to 7.0.
Feed small flake, micro pellets and frozen brine shrimp or daphnia. Keep at least six, since it is a schooling fish that gets nippy in small numbers. It sits in the middle to upper part of the tank and is mostly peaceful. Fin nipping is a risk with slow or long-finned tank mates.
Like most small tetras, it is an egg scatterer that gives no parental care. There is no solid breeding record in captivity, so it is not commonly bred at home.
Good to know
Knodus borki is a small characin in the family Characidae.
In the wild
Knodus borki lives in clear, slow forest streams of the upper Amazon basin in Colombia and Brazil. The streams are shaded by canopy, and the water is soft and slightly acidic.
Weekly picks
Tank mates
The blue 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.
Neocaridina shrimp
Neocaridina davidi
Freshwater1.6 in (4 cm) · 5 gal (19 L)59–84°F (15–29°C)
Neon tetra
Paracheirodon innesi
Freshwater1.5 in (3.8 cm) · 11 gal (40 L)70–77°F (21–25°C)
Peppered cory
Hoplisoma paleatum
Freshwater2.8 in (7 cm) · 21 gal (80 L)72–79°F (22–26°C)
Pastaza cory
Corydoras pastazensis
Freshwater2.8 in (7 cm) · 22 gal (85 L)72–82°F (22–28°C)
Striped flying barb
Esomus metallicus
Freshwater3 in (7.5 cm) · 24 gal (90 L)72–79°F (22–26°C)
Apple snail
Pomacea canaliculata
Freshwater5.9 in (15 cm) · 21 gal (80 L)64–81°F (18–27°C)
Common questions
What size tank does a blue tetra need?
A blue tetra needs at least 22 gal (85 L). It spends most of its time in the middle.
What temperature and pH does a blue tetra need?
A blue tetra is comfortable at 72–79°F (22–26°C) with a pH of 5.5–7.0.
What does a blue tetra eat?
A blue tetra eats small flake, micro pellets and frozen brine shrimp or daphnia.
How big does a blue tetra get?
An adult blue tetra reaches about 2 in (5 cm).
Does a blue tetra need a group?
Yes. A blue tetra is a schooling species and should be kept in a group, not singly.
How does a blue tetra breed?
The blue tetra is an egg scatterer and gives no parental care, like most small tetras. It has no solid breeding record in captivity and is rarely bred at home.
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)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 in (5 cm)20 gal (75 L)73–81°F (23–27°C)Rainbow emperor tetra
Nematobrycon lacortei
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)
1.8 in (4.5 cm)17 gal (65 L)68–82°F (20–28°C)Serpae tetra
Hyphessobrycon eques
1.8 in (4.5 cm) · 17 gal (65 L)