TankBud

Filament tetra

Hemigrammus filamentosus

Also known as Phoenix tetra

FreshwaterFish

Filament tetra (Hemigrammus filamentosus)
The Wet Spot Tropical Fish · Used with permission

Care at a glance

Temperature
75–82°F
24–28°C
pH
5.0–6.8
Adult size
1.7 in
4.3 cm
Minimum tank
20 gal
75 L
Temperament
Peaceful
Social behavior
Schooling
Swim level
Middle
Difficulty
Medium
Breeding
Egg scatterer
Rarity
Common
Family
Characidae
Origin
Araguaia floodplain, Brazil

Overview

The filament tetra is a peaceful schooling tetra for a dim blackwater tank. It suits a keeper with some experience.

Did you know

Filament tetras in a group spend most of the day sparring, and the bouts do no harm.

Caring for the filament tetra

Keep ten or more filament tetras so the males have rivals to display against, which keeps their fin extensions on show. Give the group at least 20 gal (75 L), set up as a blackwater tank with leaf litter and dim light.

The water should be soft and acidic, at 75 to 82°F (24 to 28°C) and a pH of 5.0 to 6.8, with gentle flow. Feed small foods they can take in midwater, such as fine flake, micro granules and frozen cyclops or daphnia.

Filament tetras are peaceful, but avoid boisterous tank mates that would damage the trailing fins. They scatter their eggs and do not guard them. Mature males extend the front rays of the dorsal and anal fins into fine filaments, which they raise during display. The filaments are the clearest way to sex the species.

Good to know

Hemigrammus filamentosus is a member of the family Characidae. The trade sells it as the phoenix tetra, for the way displaying males seem to trail flame.

In the wild

The filament tetra lives in the Araguaia floodplain in Brazil. It is found among vegetation and litter, in soft, acidic water that is often stained with tannins.

Weekly picks

Tank mates

The filament 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 filament tetra need?

A filament tetra needs at least 20 gal (75 L). It spends most of its time in the middle.

What temperature and pH does a filament tetra need?

A filament tetra is comfortable at 75–82°F (24–28°C) with a pH of 5.0–6.8.

What does a filament tetra eat?

A filament tetra eats small foods it can take in midwater, such as fine flake, micro granules and frozen cyclops or daphnia.

How big does a filament tetra get?

An adult filament tetra reaches about 1.7 in (4.3 cm).

Does a filament tetra need a group?

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

How can you tell a male filament tetra from a female?

Males extend the front rays of the dorsal and anal fins into fine filaments as they mature. Those filaments are the clearest way to tell the sexes apart.

How does a filament tetra breed?

A filament tetra scatters its eggs and does not guard them.

Related species