red eye tetra

Red Eye Tetra: Lifespan, Size, Tank Mates & More!

The red eye tetra (Moenkhausia sanctaefilomenae) is an attractive and unique freshwater species that brings a dynamic beauty to any aquarium. With their striking red eyes, shimmering metallic scales, and peaceful behavior, these tropical fish can be a joy to own.

This guide will cover everything you need to know about red eye tetra care. We’ll discuss their size, lifespan, tank mates, water parameters, and more.

red eye tetra
Red Eye Tetra with its glittering red eyes and vibrant silver body.

Species Summary

The Red Eye Tetra is a member of the Characidae family and hails from warm bodies of water in South America. These fish are native to Paraguay, Peru, Western Brazil, and Eastern Bolivia, so they can handle a wide range of temperatures and water conditions.

They’re loved by both beginner and experienced fish keepers alike due to their easy care and beautiful appearance. Red Eye tetras are known for creating flashes of sparkling colors with their shoaling nature. These stunning fish have a classic tetra shape with oval-shaped bodies and transparent fins.

The most recognizable feature of this species is their heterochromatic eyes. The top portion of their iris is bright red, while the bottom portion is gray – like the color of their body. Red Eye tetras also have a splash of yellow on the sides of their head, as well as iridescent highlights on their gills and fins.

There is also some subtle sexual dimorphism with this species. Females are typically a bit larger than the males and plump up when they’re ready to lay eggs. During the spawning season, the males may exhibit more color vibrancy.


On average, Red Eye tetras have a lifespan of about five years. This figure can vary depending on the health and quality of their living environment. For instance, if your fish were already adults when you bought them from the pet store, their lifespan could be shorter.

Poor red eye tetra care can also cause issues. Unsuitable living conditions, a poor diet, and a poorly designed home can all lead to a shorter lifespan.

Average Red Eye Tetra Size

Adult Red Eye tetras grow to about 2.75 inches in length from the tip of the tail to the snout. In rare cases, some individuals may reach three inches long.


The good news is that red eye tetra care is quite straightforward and doesn’t take a ton of effort. Despite their small size, these fish have a wide range of adaptability, making them great for newer aquarists into the fish-keeping hobby.

Tank Size

When it comes to selecting a tank size for your Red Eye tetras, aim for something around 20 gallons. This is suitable for a group of about six fish.

Of course, if you have the space and resources, you can always go bigger. Red Eye tetras are active fish who enjoy plenty of swimming room, so they’ll love being able to zip around during the day.

Water Parameters

Fortunately, these fish have relatively low maintenance water requirements. Red Eye tetras are very resilient and can handle minor fluctuations in their environment.

Your goal is to keep the water temperature between 72-82°F (22-28°C) and maintain a pH between 6.5 and 7.5. Regular water changes are a must to keep your tank clean and healthy. Aim for about 30-50% every two weeks.

In terms of water hardness, keep your levels between 4 and 18 dH. Any higher can be detrimental to the long-term health of Red Eye tetras.

Tank Mates

Red Eye Tetras are peaceful and small fish, therefore they are compatible with several other species of fish that have similar characteristics. Here are some suitable tank mates for Red Eye Tetras:

  • Neon Tetras
  • GloFish Tetras
  • Black Phantom Tetras
  • Cardinal Tetras
  • Rummy Nose Tetras
  • Otocinclus Catfish
  • Bamboo Shrimp

It’s important to note that tetras do best in a school of 6 or more, so it’s recommended to have a group of at least 6 Red Eye Tetras in your tank. Also, be sure to provide plenty of hiding spots and swimming space for all the fish in the tank.

These fish also love hiding spots and plants in their habitat, so make sure to include plenty of decorations and cover if you have a larger tank.


In terms of diet, Red Eye tetras are omnivores that prefer a balanced diet. Look for commercially prepared flake or pellet food specifically made for tropical fish. If you want to mix things up, you can also include freeze-dried worms, brine shrimp, and bloodworms.

Besides high-quality food, you should also provide occasional vegetable-based supplements such as blanched zucchini or spinach.


This species is relatively easy to breed in captivity. Simply provide your Red Eye tetras with good water conditions, plenty of hiding spaces, and the right environment. The female will lay her eggs in a dense area among plants or in caves, and the male will then fertilize them.

The eggs will hatch within 24-48 hours, and the fry should be free swimming after 5-7 days. You can start feeding them small particles such as brine shrimp and micro worms once they become mobile.


If you’re proactive about their health and nutrition, Red Eye tetras can live a long and healthy life in your aquarium. Common diseases include Ichthyophthirius, which manifests as white spots on the skin and swim bladder disorder, which causes the fish to lose balance and float upside down.

Providing your fish with a healthy diet and clean living conditions is key to avoiding these issues. Regular water changes and checkups should also be done to ensure the health of your fish.

Interesting Facts

Red Eye tetras have some interesting traits and behaviors that make them unique. For example, they are known to display a fascinating behavior known as sneezing. This involves the fish puffing out their cheeks as if they were sneezing.

This behavior is thought to be a way of cleaning the gills and releasing toxins from the water. It is also believed that this species has a special type of throat muscle that helps them catch food more efficiently.

Finally, Red Eye tetras are often seen participating in a type of courtship behavior called pairing up. When two fish come together, they will swim in circles side by side, displaying their beautiful colors.

Filter Type

When it comes to filtration, Red Eye tetras do best with a high-quality hang-on-back filter. These filters can provide powerful mechanical, biological, and chemical filtration, removing debris and maintaining ideal water parameters.

Make sure to keep the current to a moderate level so that your fish are not stressed by strong water movement.

Suitable Decor

For optimal Red Eye tetra care, you’ll want to invest in some interesting decorations and plants for your tank. Live and artificial plants can provide a natural hiding spot for the fish and add beauty to your aquarium.

You can also use bogwood or driftwood for the bottom of the tank, as Red Eye tetras enjoy hiding among the roots. Finally, a sandy substrate is best for these fish, as they like to burrow into the sand and sift through it.


When it comes to lighting, aim for subdued lighting in shades of blue for your Red Eye tetra aquarium. This will mimic their natural environment and help give the tank a more calming atmosphere.

You can also add a timer switch so that you can control when the lights turn on and off. This will give your fish plenty of time to rest when it gets dark.

Tank Maintenance

To keep your Red Eye tetras in top health, regular maintenance is a must. A weekly water change of at least 25% is recommended, and you should also clean the substrate and any decorations you have in the tank.

Try to remove any waste and uneaten food before they can rot and release toxins into the water. Once you’ve done this, test the water quality levels to make sure they’re within the parameters we mentioned earlier.

Handling Red Eye Tetras

These fish are generally peaceful and timid, so try to avoid handling them directly. If you do need to move them from one tank to another, use a net so that you don’t have to place your hands in the water.

It’s best to transport them in a separate container filled with water from their original tank to reduce the stress of the transfer.

Overall, Red Eye tetras make great additions to any freshwater aquarium. With proper care and maintenance, they can bring a whole new layer of beauty and activity to your tank. Don’t forget to provide them with a healthy diet and enjoyable environment and watch them thrive!