TankBud

January tetra

Hemigrammus hyanuary

Also known as costello tetra

FreshwaterFish

January tetra (Hemigrammus hyanuary)
Thomnight (Thomnight) · CC BY-SA 2.0 de

Care at a glance

Temperature
73–81°F
23–27°C
pH
5.5–7.0
Adult size
1.6 in
4 cm
Minimum tank
17 gal
65 L
Temperament
Peaceful
Social behavior
Schooling
Swim level
Middle
Difficulty
Medium
Breeding
Egg scatterer · Hard
Rarity
Rare
Family
Characidae
Origin
Peru, Brazil

Overview

The January tetra is a small, peaceful schooling fish for a planted soft-water community. It is a good choice once you have kept a few easier fish.

Did you know

The January tetra's wintry English name has nothing to do with the season. "January" is just an anglicized take on Januari, the Brazilian lake near where the fish was found.

Caring for the January tetra

Keep January tetras in a school of six or more, in a tank of 17 gal (65 L) or larger. A proper group keeps them calm and colored up. Set up a dim, well-planted tank, and add botanicals and a darker substrate to show them off.

Give them soft water at 73 to 81°F (23 to 27°C), with a pH of 5.5 to 7.0. Feed small flake and micro pellets, with the occasional frozen brine shrimp or daphnia.

January tetras are peaceful and active, so keep them alongside other small, gentle fish. They are egg scatterers and give no parental care. The eggs hatch in about a day to a day and a half, but breeding them is hard.

Good to know

Hemigrammus hyanuary is a characin in the family Characidae, also sold as the costello tetra. It has a slim, silvery body with a dark stripe and a small gold or green mark near the tail. The species is listed as Least Concern, with stable wild numbers.

In the wild

The January tetra comes from calm, shallow Amazon waters in Peru and Brazil, including the Lago do Januari area near Manaus. These are soft, slightly acidic, shaded spots over sand or mud, rich in plants and biofilm.

Weekly picks

Tank mates

The January tetra is a 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.

Check the full mix in the stocking calculator

Common questions

What size tank does a January tetra need?

A January tetra needs at least 17 gal (65 L). It spends most of its time in the middle.

What temperature and pH does a January tetra need?

A January tetra is comfortable at 73–81°F (23–27°C) with a pH of 5.5–7.0.

What does a January tetra eat?

A January tetra eats small flake and micro pellets. Add the occasional frozen brine shrimp or daphnia.

How big does a January tetra get?

An adult January tetra reaches about 1.6 in (4 cm).

Does a January tetra need a group?

Yes. A January tetra is a schooling species and should be kept in a group, not singly.

How does a January tetra breed?

January tetras scatter their eggs and leave them without any care. The eggs hatch in about a day to a day and a half, and breeding the fish is hard.

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