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

Red eye tetras are a lovely freshwater species that can be a joy to own. Aside from their striking appearance, these fish can also be playful and easygoing.

This guide will teach you everything you need to know about red eye tetra care. We go over their size, lifespan, ideal tank mates, water parameters, and more!

Species Summary

The red eye tetra (Moenkhausia sanctaefilomenae) is a popular species in the fishkeeping trade. A member of the Characidae family, these fish are beginner-friendly. Yet, they’re also beloved to seasoned aquarists looking for a no-frills freshwater fish that adds dynamic beauty to a well-designed tank.

A single red eye tetra

Known for their shoaling nature, these fish can create flashes of shimmering metallic that move through your tank. Pops of red, black, and white create a unique look that spices up any aquarium.

Red eye tetras come from warm bodies of water in South America. They’re most commonly found in calm rivers and streams throughout Paraguay, Peru, WWesternBrazil, and Eastern Bolivia. Their natural distribution is wide, leading to an adaptive lifestyle perfect for life in captivity.

It doesn’t matter whether this is your first time owning a tropical freshwater fish or you’re an experienced fish-keeper looking to add some vibrant beauty to a community tank. Red eye tetra care is very straightforward, and this species has a lot to offer.

No Spam, Subscribe for Cool Fish Stuff!

* indicates required


This species’ appearance is in its name! The most recognizable characteristic of this fish is its signature red eyes. Interestingly enough, only the top portion of the iris is red-colored. The rest is gray, matching the color of the body.

The heterochromatic nature of the eye is captivating, adding to the fish’s distinct look.

As for the body, it’s a classic tetra shape. These fish have oval-shaped bodies covered in shimmery metallic scales. Look closely, and you may notice some subtle color details.

For example, most fish have a splash of yellow tinge on the sides of the head. Iridescent highlights on the gill plate and fins are pretty common, too. The fins are otherwise transparent, allowing the flashes of sparkle to stand out in the right lighting conditions.

Like many types of tetras, red eyes have an expansive anal fin that stretches across the lower body. There’s also a tiny adipose fin up top!

The caudal fin has some more distinct coloration. While the tips of the forked tail are transparent like the rest of the fins, a big black with a small highlight of white appears at the caudal fork. This detail adds some contrast against the metallic scales.

Author Note: Red eye tetras exhibit some subtle sexual dimorphism. Typically, the females are a bit girthier than the males. The male fish also experience more color vibrancy around mating season while the females plump up with eggs.


The average red eye tetra lifespan is around five years. But as you probably know, there’s no guarantee. Adult fish bought at a local pet shop could be several years old already, leading to a shortened lifespan in your home aquarium.

Furthermore, red eye tetras are prone to disease and ill health with improper care. Unsuitable living conditions, a lackluster diet, and a poorly designed home could lead to a shortened lifespan.

Average Red Eye Tetra Size

Red eye tetras are on the smaller end of the size spectrum. The average red eye tetra size is around 2.75 inches in length for adults. This measurement is from the tip of the tail to the snout.

Author Note: Some fish will get up to three inches long on rare occasions, but those instances are few and far between.


If you’re interested in owning some red eye tetras for yourself, you’re in luck! These fish are very adaptable and can live in a wide range of conditions. They’re surprisingly resilient, making red eye tetra care very approachable for newer fish-keepers.

Of course, red eye tetras have their preferences. To ensure that your fish live happy and healthy lives, here are some care guidelines you need to follow.

Tank Size

One of the first crucial decisions you’ll need to make is how big of a tank you’ll need to get. Because red eye tetras are so small, they don’t need a ton of space to be happy! They can do just fine in relatively compact aquariums.

Most experts recommend a tank that holds at least 20 gallons of water. That size is suitable for a small group of about six fish.

Author Note: If you want to own more or make your red eye tetras a part of a larger community fish setup, go bigger! This species is active and will appreciate the extra swimming space to zip around during the day.

Water Parameters

The best part of red eye tetra care is that these fish have relatively lax water requirements. While some other freshwater fish are sensitive to minute changes in water conditions, that’s not the case with these tetras. They’re adaptable to standard tropical tank setups.

As a result, you don’t have to spend a ton of time ensuring that pH levels, temperatures, and hardness readings are in a precise range. As long as you stick close to the following parameters, you should be good to go!

  • Water temperature: 72°F to 84°F (Around 79 or 80 degrees is ideal) 
  • pH levels: 5.5 to 8.5 (Stay close to 7.0 neutral)
  • Water hardness: 4 to 8 KH

Author Note: As always, invest in a reliable and accurate water test kit so you can check these parameters regularly. You need accurate readings if you want your red eye tetras to thrive.

What To Put In Their Tank

This is the part of red eye tetra care where you can get creative. These fish can get used to most natural-style setups. However, a home modeled after their natural habitat is always best.

These fish come from slow-moving rivers and streams in South America. Typically tree roots create a labyrinth of hiding places beneath the water’s surface. Meanwhile, tree branches and leaves offer plenty of shade from up above.

A shoaling group of red eye tetras

You don’t have to create a completely dark environment, but offering tons of shade and hiding spots is always a plus. The best way to do that is to decorate your tank with floating plants, rock structures, driftwood, and any other natural-looking piece of decor.

For the substrate, it’s best to choose something dark. The rivers these fish come from are often littered with detritus and decaying leaves, leaving the floor almost black.

Of course, red eye tetras don’t spend a ton of time at the bottom of fish tanks. They prefer to linger in the middle of the water column. As a result, feel free to choose a substrate that works for live plants or any bottom-dwellers you plan to keep in the community.

Author Note: When it comes to pumps and filters, aim them strategically to prevent heavy water flow. Red eye tetras prefer relatively stagnant water conditions.

Common Possible Diseases

Fortunately, red eye tetras don’t suffer from uncommon diseases that only plague their species. However, they’re still susceptible to all the usual health problems that freshwater fish face (which shouldn’t be surprising).

We’re talking about health issues like Ich, fungal infections, fin rot, and more. Ich is usually the biggest problem with red eye tetras. It’s a contagious condition that results in white spots forming all over the body.

If you don’t treat it fast enough, Ich can spread to your entire community of fish, killing them all!

Luckily, treating Ich is pretty simple, and red eye tetras are responsive to over-the-counter medications. All you have to do is quarantine infected fish, provide treatment, and wait things out. The same goes for most other common health conditions.

Author Note: Most of the health problems that red eye tetras succumb to are due to poor water conditions. Make sure to check the temperature, hardness, and pH balance periodically to ensure that things are within the accepted range. Also, maintain the filtration system and replace 25 to 50 percent of the water every other week to keep ammonia and nitrates under control.

Food & Diet

Red eye tetras are natural omnivores. They eat everything from live insects to plant detritus floating in the water in the wild. A varied diet is essential for providing balanced nutrition and essential nutrients.

You can start with a commercial flake or pellet food when you’re getting started. There’s no shortage of balanced formulas out there, and some manufacturers make them specifically for tetras. They’re a good place to start, but most seasoned fish enthusiasts will tell you that supplementing with high-quality foods makes all the difference in their health.

That’s why it’s a good idea to go with a mix of plant-based and meat-based foods. For meats, live, frozen, and freeze-dried products are all suitable. You can provide your tetras with bloodworms, brine shrimp, Daphnia, tubifex worms, and more. For vegetables, try blanched spinach, peas, or cucumbers.

Red eye tetras have a strong appetite. Two to three meals every day are necessary to keep them happy and healthy. Only provide as much food as the fish can eat in three meals. Otherwise, they may overeat or leave the food to sour the water.

Behavior & Temperament

Red eye tetras are easy-going and active. However, you’ll only see this thriving behavior if you have a group of at least six. These fish thrive in a group setting, and having too few fish may lead to shyness and anxiety.

Moenkhausia sanctaefilomenae

In groups of six or more, the tetras will swim together and create a dance of shimmering light and color. They’re not strictly schooling fish, so don’t be surprised if you see them separate and do their own thing.

Usually, red eye tetras stick to the middle of the water column and swim among plants or hiding places. If you have slow-moving fish or species with flowing fins, you may notice slight aggression. Red eye tetras can nip fins, so you’ll want to keep an eye on vulnerable fish.

Red Eye Tetra Tank Mates

This small and playful fish does very well in a community tank. However, you have to be strategic in choosing tank mates.

As mentioned earlier, slow-moving fish and long delicate fins could be problematic. Not all red eye tetras will try to nip their fins, but it’s a pretty common issue that you shouldn’t risk.

Instead, try keeping these tetras with like-minded species. Other active fish of similar size and temperament are great options. You can also look for peaceful bottom-dwellers and surface skimmers. Red eye tetras will usually stay out of their way.

Of course, always avoid larger or more aggressive fish. Red eye tetras won’t survive in tanks with cichlids or other violent species.

Need some inspiration on creating a community tank? Here are some fantastic red eye tetra tank mates.


Breeding red eye tetras in captivity isn’t too difficult. These fish will naturally pair off and may lay eggs unprovoked. But if you want to breed them intentionally, it’s best to do so in even groups of about twelve fish.

Separate the males and females for about a week. During that week, condition the fish with plenty of live, protein-rich foods.

In the meantime, create a breeding tank. It should hold about 20 gallons and have similar water conditions to the standard tanks. Slightly warmer temperatures are ideal.

Keep the light levels low and add plenty of places for the eggs to hide. Red eye tetras don’t have many parental instincts, so they may eat the eggs shortly after the female lays them. Placing floating aquarium plants, java moss, or even a breeding net will give the eggs a fighting chance.

Transfer the conditioned fish into the breeding tank in the evening. By morning, they should perform the breeding ritual. The fish will roll around in the vegetation before the female releases about a dozen eggs.

After they’re done, remove the adult fish and let the eggs incubate. They should hatch after a day or two. After the babies eat the egg sacs, provide Daphnia or powdered fry food. As the fry gets bigger, you can move to freshly hatched brine shrimp and other commercial foods.


Red eye tetra care can be managed by anyone. As long as you have the willingness to give these beautiful fish the attention they deserve, you shouldn’t have any trouble helping them thrive.

If you have any questions about caring for these fish, we’re more than happy to hear from you. Send us a message and we’ll get back to you as soon as we can!

You May Also Like