Blue tetra

Care at a glance

Overview

Keep this one in a group of six or more; it's a schooling fish and gets nippy when kept in small numbers. It sits in the middle to upper part of the tank and is mostly peaceful, though fin-nipping is a risk with slow or long-finned tankmates. An 85 liter tank gives a group room to school. Feed small flake, micro-pellets, and frozen brine shrimp or daphnia. Keep pH from 5.5 to 7.

In the wild

This blue tetra lives in clear, slow forest streams of the upper Amazon basin in Colombia and Brazil, shaded by canopy with soft, slightly acidic water. Aim for the same dim, soft setup: subdued lighting, some plants, and tannin-stained water if you can manage it. Temperatures in the low to mid 20s C suit it.

Good to know

Knodus borki is a small characin in the family Characidae, reaching about 5 cm. Like most small tetras it's an egg scatterer that gives no parental care. There's no solid breeding record in captivity for this species, so it's not commonly bred at home.

Did you know

Knodus is a confusing genus, and fish sold as "blue tetra" often turn out to be several different species mixed together. Borki was only described in 2008, so a lot of older aquarium info under that common name actually refers to other fish.

Related species

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  Emperor tetra

  Nematobrycon palmeri

  2 in (5 cm)20 gal (75 L)73–81°F (23–27°C)

• 

  Glass tetra

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  2 in (5 cm)18 gal (70 L)75–82°F (24–28°C)
• Green fire tetra

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  2 in (5 cm)20 gal (75 L)72–79°F (22–26°C)
• Rainbow emperor tetra

  Nematobrycon lacortei

  2 in (5 cm)20 gal (75 L)73–81°F (23–27°C)

• 

  Bloodfin tetra

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  2.2 in (5.5 cm)20 gal (75 L)72–82°F (22–28°C)

• 

  Black widow tetra

  Gymnocorymbus ternetzi

  2.4 in (6 cm)20 gal (75 L)68–79°F (20–26°C)