Max Size: 6cm

Blackline Tail Tetra (Moenkhausia costae)

Blackline Tail Tetras are a peaceful and very sociable community fish. These Tetras are hardy species that are tolerant of a wide range of water conditions. However, you will need to make sure that you keep these fish in an aquarium with a tight-fitting lid as they are likely to jump.

These Tetras are very active schooling fish and will thrive if kept in a larger group of at least six individuals. They will express more natural behaviour and better colours, especially when persuing the females for attention.

Blackline Tail Tetras can live in a community aquarium with many different species without difficulty. However, it would be best not to place them with species that have elaborate finnage as these Tetras can be a tad nippy at times.

Ideal tank mates for these fish would be other South American characins and bottom-dwellers. However, it would be better if you did not house these Tetras with much larger or more aggressive species otherwise, they will get stressed and outcompeted for food.

Blackline Tail Tetras prefer a densely planted aquarium containing a dark substrate and background to best show off the subtle colours of these fish. These fish also require plenty of swimming space and some subdued lighting.

Blackline Tail Tetras have a semi-translucent silvery to a green sheen on their body and transparent fins. In addition, their caudal and anal fin has a unique stripe pattern running through them that displays a perfectly even diagonal line.


Blackline Tail Tetra
Quick Facts
Scientific NameMoenkhausia costae
Other NamesCostae Tetra
Aquarium LevelMiddle - Top
DifficultyBeginner - Intermediate
Best kept asGroups 6+
Lifespan3 - 5 years
Water Parameters
Water TypeFreshwater
PH6.0 - 7.5
GH5 - 18
TDS18 - 268
72 - 79℉
22.2 - 26.1℃

Natural Habitat

São Francisco River


In the home aquarium, the Blackline Tail Tetra will readily accept most good quality dried foods such as granules, flakes and sinking pellets. These modern food products have been developed to provide all adequate nutrition to maintain your fish's health and dietary requirements.

Providing additional foodstuffs such as live, frozen, and freeze-dried meals such as bloodworm, daphnia, and tubifex once or twice a week will provide additional benefits to your fish's health and well-being but is not a must for this fish.

It should be noted that bloodworms should only be given as an occasional treat and should not be used as the staple diet as they are difficult for fish to digest and can potentially cause blockages.

This fish is an omnivore in the wild, meaning it will consume some vegetable matter. Although most modern fish foods take this into account and include them in their products, you can still supplement your fish's diet with blanched vegetables such as spinach, broccoli, and zucchini. Ensure you do not overfeed your fish and remove any leftovers the following day.

Sexual Dimorphism

It is relatively challenging to distinguish the males from female Blackline Tail Tetras. The males are usually a bit smaller and are more brightly coloured than females, and their bodies are somewhat more slender than rounded. In contrast, the females are slightly duller, somewhat larger, and their stomachs are plumper and rounder.

Other Tetras of interest

Adonis Tetra(Lepidarchus adonis)
African Moon Tetra(Bathyaethiops caudomaculatus)
African Red Eyed Tetra(Arnoldichthys spilopterus)
Arowana Tetra(Gnathocharax steindachneri)
Black Darter Tetra(Poecilocharax weitzmani)
Black Line Tetra(Hyphessobrycon scholzei)
View all Tetras
Date Added: 12/10/2021 10:28:00 - Updated: 08/08/2022 16:05:10