Red Eye Tetras

Red Eye Tetra Care Guide

One variety of tetra that we are particularly fond of is the red eye tetra. This little fish has beautiful red eyes that really stand out against its silver body.

Today, we want to share some information about the care and keeping of these significant species.

So, in this guide,  we are going to talk about everything you need to know about red eye tetras including their diet, Habitat, and tank mates.


Scientific NameMoenkhausia Sanctaefilomenae
OriginRivers of western Brazil, Eastern Peru, Paraguay, and Eastern Bolivia.
Minimum Tank Size20 gallon
Length2.7-2.8 inches (6 cm)
Ease of CareEasy
pHBetween 5.5 and 8.5.
TemperatureRange between 73 and 82 degrees Fahrenheit

Red Eye Tetras Origins & Habitat

The redeye tetra (Moenkhausia sanctaefilomenae), a species of tetra from the São Francisco, upper Paraná, Paraguay, and Uruguayan river basins in eastern and central South America.

This freshwater fish is often raised in commercial facilities throughout Eastern Europe and Asia.

They are known for their shoaling nature and will often form large schools of fish in the wild.

What Are the Features of Red Eye Tetra?


As its name suggests, the most distinctive feature of this species is its bright red eyes.

The top portion of the iris is colored red, while the bottom is gray. This unique coloration makes the red-eye tetra stand out among other freshwater fish.

The heterochromatic condition of the eye is fascinating, contributing to the fish’s unique appearance.

The body is a traditional tetra shape that is oval and dotted with glittering metallic scales.

Like many tetras, red eyes have an expansive anal fin that stretches across the lower body.

There’s also a tiny adipose fin up top, while the caudal fin has a distinct coloration.

The tips of the forked tail are translucent, as are the other fins, but a big black with a small white highlight appears at the caudal fork. Thanks to this element, the gold scales have a sharp contrast.


The average red eye tetra size is around 2.75 inches in length for adults, though some may grow to be up to 3 inches long. This measurement is from the tip of the tail to the snout.

Red-eye tetras are on the smaller end of the size spectrum, making them popular for those with smaller aquariums.


As you probably know, the average red eye tetra lifespan is around five years.

However, several factors can influence a red-eye tetra’s lifespan, including care and diet.

For example, adult fish bought at a local pet shop could be several years old, leading to a shortened lifespan in your home aquarium.

Also, unsuitable living conditions, a lackluster diet, and a poorly designed home could shorten your red-eye tetra lifespan.

However, with proper care, you can help your red-eye tetra live a long and healthy life.

Is Red Eye Tetra Hardy?

If you are looking for a small, colorful fish to add to your aquarium, you may want to consider the red-eye tetra.

These little fish are beautiful, but they are also quite hardy and easy to care for.

Red-eye tetras make a great addition to any community tank and can provide hours of enjoyment for you and your family.

Red Eye Tetra Availability

This fish is a common aquarium fish that may be bred in quantity at commercial hatcheries in Eastern Europe and Asia. So, they are readily available in the aquarium trade.

They can be found in any pet stores and online retailers. Prices vary depending on the retailer, but they are generally affordable.

How to Care for Red Eye Tetra?

1. Tank Size

Because red eye tetras are so small, they don’t need much space to be happy! They can do just fine in relatively compact aquariums.

We recommend a tank that holds at least 20 gallons of water.

However, if you want to own a large group or make your red-eye tetras a part of a more extensive community fish setup, you’ll need a bigger tank.

This species is active and will appreciate the extra swimming space to zip around during the day.

2. Temperature

This species is found in the wild in South America, specifically in the Orinoco Basin.

Their natural habitat has a variety of temperatures, so they are adaptable to different environments.

However, it is essential to maintain a consistent temperature to keep them healthy and comfortable.

The ideal water temperature for red-eye tetras can range between 73 and 82 degrees Fahrenheit.

If the temperature drops below 73 degrees, they may become sluggish and listless.

At the same time, if it rises above 82 degrees, they may become stressed and more susceptible to disease.

Maintaining a consistent temperature will keep your red-eye tetras happy and healthy.

3. PH Level

The best part of red-eye tetra care is that these fish have relatively lax water requirements.

They can thrive in a wide range of pH levels, from 5.5 to 8.5.

This makes them ideal for beginner aquarists who may not yet have a handle on keeping their water parameters stable.

4. Lighting

In the wild, the Red Eye Tetra’s habitat doesn’t have a lot of light because the shores of their rivers have lots of greenery. Because of this, it’s better if their tank has soft lighting.

You can achieve this by putting some fluctuates in the water. This will help your Red Eye Tetra feel more comfortable and at home.

5. Filters

Red-eye tetras prefer relatively stagnant water conditions. So, when it comes to filters and pumps, aim them strategically to prevent heavy water flow.

A canister filter with a low flow rate is ideal for a red-eye tetra aquarium.

As for filtration media, use a combination of mechanical and biological filtration.

This will help keep the water clean and straightforward while providing a healthy environment for your red-eye tetras to thrive.

6. Tank Decoration

When it comes to decorations, a dark substrate is best since it mimics the rivers these fish come from.

After adding the dark substrate, add some floating plants, rock structures, driftwood, and another natural-looking decor.

This will create an excellent environment for your fish to swim around.

Red Eye Tetra Diet

A varied diet is essential for providing balanced nutrition and vital nutrients for red-eye tetras.

An excellent place to start is with a commercial flake or pellet food, but supplementing with high-quality foods such as live insects or plant detritus will make a big difference in their health.

For live foods, consider options such as:

  • Bloodworms
  • Brine shrimp
  • Daphnia
  • Tubifex Worms

Also, blanched spinach, peas, and cucumbers are excellent plant matter choices.

Feed two to three times per day, only giving as much food as the fish can eat in a few minutes. This will help prevent overeating and keep water quality high.

Red Eye Tetra Compatibility

Red-eye tetras are not aggressive fish and will not bother other fish in the aquarium.

They are docile and can be maintained alongside other calm fish of comparable size.

However, they occasionally bite at the fins of slow-moving, long-finned fish, which isn’t something to worry about.

They perform best in groups or alone, and they’re a fantastic addition to any aquarium’s ecosystem.

Red Eye Tetra can be kept with the following fish:

  • Barbs
  • Rainbowfish
  • Danios
  • Larger Types Of Rasboras

Red Eye Tetra Gender Difference

Regarding sexual differences, red-eye tetras are not too different from other tetra species.

Females tend to have larger, more rounded abdomens, and when they are sexually mature, their bellies fill with eggs.

Meanwhile, males become much more colorful when they are ready to mate.

So when breeding red eye tetras, be sure to select the brightest males.

Red Eye Tetra Breeding

If you’re thinking about breeding your red-eye tetras, there are a few things you’ll need to keep in mind.

First, you’ll need to set up a separate breeding tank with slightly acidic water (pH 5.5 to 6.5) and very soft water (4 dGH or below).

A 20-gallon tank is typically sufficient, and you’ll need to maintain a temperature of 80 to 84 degrees Fahrenheit (26.6 to 29.0 degrees Celsius).

Once your breeding tank is set up, you’ll need to add a few plants to help provide cover for the fry (baby fish) once they’re born.

Java moss is a good option, as it’s easy to care for and can tolerate a wide range of water conditions.

When you’re ready to breed your red-eye tetras, simply introduce a group of 6 to 8 fish to the breeding tank.

It’s best to have more females than males, as the males can be pretty aggressive when it comes to spawning.

Once the fish are in the breeding tank, they should start to spawn within a few days.

The female red eye tetras will lay their eggs on the plants, and the male fish will fertilize them.

The fry will hatch a few days later, and they should be fed small live foods such as brine shrimp or mosquito larvae.

Once they’re a bit older, you can start to feed them crushed flake food or pellets.

Your red-eye tetras should thrive and provide you with more generations of these beautiful fish with proper care.

Possible Diseases and Prevention

Unfortunately, like any other fish, red-eye tetras are susceptible to a number of diseases.

The most common issues include Ich, fungal infections, and fin rot.

Ich is a contagious condition that causes white spots to form all over the body.

If not treated promptly, it can be fatal. Keep your red-eye tetra’s tank clean and maintain a stable water temperature to prevent Ich.

Fungal infections are another concern for red-eye tetras.

These can be caused by dirty water or stress. Fin rot is a bacterial infection that can cause the fins to rot away.

Fungal infections usually precede it.

Keep the tank clean and stress-free to prevent diseases and health problems in red-eye tetras.

Regular water changes and a good filter will go a long way in keeping your fish healthy.

Be sure to quarantine new fish before adding them to the tank.

And lastly, don’t overfeed! A well-balanced diet is essential for keeping red eye tetras healthy.

Last Words

The red-eye tetra is a prevalent fish, and for a good reason! They are relatively easy to care for and make a beautiful addition to any aquarium.

We hope you enjoyed reading this article and found it helpful in your quest to learn more about these beautiful fish.

If you still have any questions, please feel free to leave comments below.