Costae tetra
Moenkhausia costae
Also known as Blackline moenkhausia, Blackline tail tetra, Black line tail tetra
FreshwaterFish
Care at a glance
- Temperature
- 72–82°F
- 22–28°C
- pH
- 6.0–7.5
- Adult size
- 2.8 in
- 7 cm
- Minimum tank
- 29 gal
- 110 L
- Temperament
- Peaceful
- Social behavior
- Schooling
- Swim level
- Middle
- Difficulty
- Easy
- Breeding
- Egg scatterer
- Rarity
- Common
- Family
- Characidae
- Origin
- São Francisco and Itapicuru basins, Brazil
Overview
The Costae tetra is a hardy schooling tetra for a robust community, not a delicate blackwater display. It is easy to keep.
Did you know
The Costae tetra's tail blade flicks like a signal flag. Brazilian keepers call the look a swordtail-tetra without any sword.
Caring for the Costae tetra
Keep eight or more Costae tetras in 29 gal (110 L) or larger. Give them open swimming space, some planting and moderate flow.
The Costae tetra suits harder water than most of its relatives, which makes it useful where the tap water is not soft. Keep it at 72 to 82°F (22 to 28°C), with a pH of 6.0 to 7.5. It is completely undemanding about food and takes flake, granules and frozen fare.
It is peaceful and active, and safe with other community fish. It is an egg-scattering spawner and does not guard its eggs.
Good to know
The Costae tetra, Moenkhausia costae, is a member of the family Characidae. It carries a black stripe running the length of the body into the tail, with a yellow wash above it.
In the wild
Moenkhausia costae lives in the São Francisco and Itapicuru basins of eastern Brazil. These drainages run harder and more neutral than the Amazon, and they hold a distinct fish fauna of their own.
Weekly picks
Tank mates
The Costae 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.

Red tail sicyopterus
Sicyopterus lagocephalus
Freshwater5.1 in (13 cm) · 29 gal (110 L)73–81°F (23–27°C)
Redfin halfbeak
Nomorhamphus ebrardtii
Freshwater3.5 in (9 cm) · 29 gal (110 L)75–81°F (24–27°C)
Bunau barb
Barbodes bunau
Freshwater3.5 in (9 cm) · 29 gal (110 L)72–81°F (22–27°C)
Giant otocinclus
Hypoptopoma psilogaster
Freshwater3.1 in (8 cm) · 29 gal (110 L)75–82°F (24–28°C)
Silver hatchetfish
Gasteropelecus levis
Freshwater1.4 in (3.5 cm) · 30 gal (112 L)73–82°F (23–28°C)
Kallman's swordtail
Xiphophorus kallmani
Freshwater4.1 in (10.5 cm) · 29 gal (110 L)73–82°F (23–28°C)
Common questions
What size tank does a Costae tetra need?
A Costae tetra needs at least 29 gal (110 L). It spends most of its time in the middle.
What temperature and pH does a Costae tetra need?
A Costae tetra is comfortable at 72–82°F (22–28°C) with a pH of 6.0–7.5.
What does a Costae tetra eat?
A Costae tetra is completely undemanding about food. It takes flake, granules and frozen fare.
How big does a Costae tetra get?
An adult Costae tetra reaches about 2.8 in (7 cm).
Does a Costae tetra need a group?
Yes. A Costae tetra is a schooling species and should be kept in a group, not singly.
How does a Costae tetra breed?
The Costae tetra scatters its eggs and does not guard them.
Related species
2.6 in (6.5 cm)20 gal (75 L)73–81°F (23–27°C)Napo tetra
Moenkhausia naponis
2.6 in (6.5 cm) · 20 gal (75 L)
3.1 in (8 cm)24 gal (90 L)75–82°F (24–28°C)Green-eye tetra
Moenkhausia chlorophthalma
3.1 in (8 cm) · 24 gal (90 L)
2.4 in (6 cm)20 gal (75 L)73–82°F (23–28°C)Cope's tetra
Moenkhausia copei
2.4 in (6 cm) · 20 gal (75 L)
2.4 in (6 cm)20 gal (75 L)73–82°F (23–28°C)Preto tetra
Moenkhausia pretoensis
2.4 in (6 cm) · 20 gal (75 L)
3.3 in (8.5 cm)29 gal (110 L)72–81°F (22–27°C)Bonita tetra
Moenkhausia bonita
3.3 in (8.5 cm) · 29 gal (110 L)
3.4 in (8.7 cm)29 gal (110 L)75–84°F (24–29°C)Heiko's tetra
Moenkhausia heikoi
3.4 in (8.7 cm) · 29 gal (110 L)
