Max Size: 7cm

Red Eye Tetra (Moenkhausia sanctaefilomenae)

The Red Eye Tetra is peaceful, very active, relatively hardy and easy to take care of as they can adapt to a wide range of water parameters, making them perfect for a beginner aquarist who wants to add a touch of elegance to a community aquarium. These Tetras are tough enough to be indecisive and big enough not to get eaten by other species with a big mouth.

Red Eye Tetras are schooling fish in nature, so they should be kept in a group of at least six individuals, preferably more. Keeping these Tetras in more significant numbers will give you a better looking natural display. However, if you keep these Tetras in too small a group, they may become withdrawn and start to show aggression to other fish species.

Ideal tankmates for Red Eye Tetras could include other similarly sized Tetras, larger Rasboras, Rainbowfish, Barbs, and most Danios. In addition, bottom dwellers such as Corydoras Catfish and Botia Loaches will also make excellent tankmates.

Red Eye Tetras can also be used as a dither fish for non-agressive medium-sized Cichlids. However, it would be best if you avoided slower, more timid species such as Gouramis and Dwarf Cichlids; otherwise, they will feel intimidated by their boisterous activity.

Red Eye Tetras will thrive in most well-maintained tanks, although these fish do not like very bright lighting or lightly decorated surroundings.

Red Eye Tetras would look stunning in either a well-planted aquarium or an aquarium designed to mimic an Amazonian biotope setup. You will need a sandy substrate, driftwood branches, and twisted roots to achieve this result. It would also be beneficial to add dried leaves such as beech or oak, as this will add to the natural feel.

The Red Eye Tetra has a bright silver body accentuated by black colouring on the base of the caudal fin edged with white. In addition, these Tetras have a thin bright red circle around their eye.

Tank Mates for the Red Eye Tetra

2 ideal tank mate ideas for the Red Eye Tetra include:

Black Widow Tetra(Gymnocorymbus ternetzi)
Denison Barb(Sahyadria denisonii)
Quick Facts
Scientific NameMoenkhausia sanctaefilomenae
Year Described1907
Other Nameslamp eye tetra.
OriginsArgentina, Brazil, Paraguay, Uruguay
Aquarium LevelMiddle - Top
Best kept asGroups 5+
Lifespan3 - 5 years
Water Parameters
Water TypeFreshwater
PH5.5 - 8.5
GH5 - 20
KH4 - 8
TDS100 - 200
75 - 85℉
23.9 - 29.4℃

Photos of the Red Eye Tetra

Red Eye Tetra
Red Eye Tetras
Red Eye Tetras Spawning
Eye Tetra Fish
Red Eye Tetra
Red Eye Tetra
Red Eye Tetra

Natural Habitat

Red Eye Tetras are endemic to Brazil, Paraguay and Argentina in South America. In eastern and central South America, you will find them in the Sao Francisco, upper Paraná, Paraguay and Uruguay River Basins. These fish inhabit moderately flowing clear waters of big rivers but can also be found in the thick vegetation of the murky Amazon.

São Francisco River

What to feed the Red Eye Tetra

Red Eye Tetras are unfussy and will readily accept just about anything offered. However, for the best colours and condition of your fish, offer them frequent meals of small live, frozen and freeze-dried foods such as daphnia, bloodworm and brine shrimp. You should supplement these foods with good quality dried food such as flakes and granules and include some vegetables in their diet; spinach leaves or blanched courgette are ideal.

How to sex the Red Eye Tetra

It can be somewhat challenging to differentiate between the male and female Red Eye Tetra. However, the females are often slightly larger and are much more rounder in the stomach than males, especially when they are full of eggs.

How to breed the Red Eye Tetra

Like most Moenkhausia species, if Red Eye Tetras are in good condition, they can spawn in a community aquarium, and small numbers of fry may start to appear without any human intervention. However, like all Tetras, they are egg scattering free spawners that present no parental care.

If you would like to produce a higher yield of fry, it would be better if you prepared a separate breeding tank. The breeding tank will need dim lighting, established water, and plenty of plants; spawning mops will work just as well. However, it would be better if you also conditioned the breeding pairs with plenty of live, frozen or freeze-dried foods such as bloodworm or mosquito larvae; this will help to encourage reproduction.

When females are ready to spawn, you will notice them swimming more actively around the tank and the males bumping into them. The fish will then lock fins and carry out a somersault movement in the plants where the female will scatter her eggs, and the male will fertilise them.

Typically when the females lay their eggs, they lay them in plants; however, some eggs may drop to the bottom of the tank. Females can lay several hundred eggs during a single spawning.

Once the females have stopped scattering their eggs and the males have fertilised them, it is advisable to remove the adults from the breeding tank because they will have nothing more to do with the eggs, and they may consume them if given a chance.

It would be better to keep the lights off, and the tank dark as Tetra eggs and fry are especially susceptible to the light. Generally, the eggs will hatch somewhere between 24 and 48 hours depending on the temperature; then, three to four days after that, the fry will become free-swimming. So, after the first week or so, you may gradually start to increase the lighting.

The newly hatched fry will first feed on their yolk sac, but once they have consumed their yolk sack and become free-swimming, you can provide them with rotifers or infusoria moving on to baby brine shrimp and crushed flakes as they grow.

Other Tetras of interest

African Moon Tetra(Bathyaethiops caudomaculatus)
African Red Eyed Tetra(Arnoldichthys spilopterus)
Black Darter Tetra(Poecilocharax weitzmani)
Black Line Tetra(Hyphessobrycon scholzei)
Black Neon Tetra(Hyphessobrycon herbertaxelrodi)
Black Phantom Tetra(Hyphessobrycon megalopterus)
View all Tetras
Date Added: 28/05/2020 - Updated: 15/03/2022 17:30:30