Freshwater Fish

Luminous Tetra – Hemigrammus erythrozonus: Care Guide, Tank Mates, Breeding & More

Luminous tetras are one of our favorite freshwater species. They are colorful, active, easy to care for and fun to watch!

Because of this, we find ourselves recommending them to other aquarists all the time. They are a great choice for beginners or experienced owners who want to care for a low-maintenance fish.

This guide goes over light tetra care in great detail. You’ll learn about their diet, tank mates, lifespans, and even how to breed them!

Species Summary

Since its introduction to the pet trade in 1933, the glowlight tetra (scientific name: Hemigrammus erythrozonus) has been a favorite among aquarists around the world. Take a look at this beauty and it’s not hard to see why!

Because these are such colorful fish, they can really liven up the look of any freshwater aquarium. As a schooling species, luminous tetras regularly group together and dart around the tank to create a striking display of color.

The glowlight tetra is endemic to the rivers of Guyana in South America. They inhabit rivers and streams of black water. Like many freshwater species in this area, glow tetras are surprisingly hardy and easy to care for.

Light Tetra Appearance

The luminous tetra has a torpedo-shaped body. At first glance, it looks a lot like its more popular cousins, the neon tetra and the cardinal tetra.

However, most of the body is semi-transparent. It takes on a silver base color that can be seen through. This becomes quite apparent when you look at them closely.

But the most identifying feature of this species is its reddish-orange stripe! The stripe runs laterally along the entire length of the fish. It runs from the front of the head to the tip of the tail.

Author’s Note: The ray looks like a light bulb filament, which is why this species got its common name.

In the right lighting conditions, the stripe will really shine! You will also notice the same color on the edge of the dorsal fin. All other fins are transparent.

An interesting thing about this line is that it even goes through the eye. Most of the eye is silver to match the rest of the body. But the upper iris has the bold coloration the fish is known for.

The differences between male and female luminous tetras are subtle. Females are usually slightly larger and have a plumper body shape.

Life expectancy

The average lifespan of the light tetra is between two and four years when given proper care. This is definitely on the shorter side of things when you compare them to other tetra species.

Like any other freshwater species, incandescent lights will react negatively to poor diets, dirty tanks, and poor water conditions. To keep your fish happy and healthy for as long as possible, you need to be vigilant in providing top-notch care.

Author’s Note: Buying your fish from a reputable seller will also increase the chances of a long shelf life. Do your homework!

Average size

The typical size of a light tetra is around 1.5 inches long when fully grown. These are tiny creatures, which makes them great fish for nano tanks.

Some specimens will get slightly larger, reaching lengths of up to two inches. However, those cases are few and far between.

We always enjoy it when small fish like this are colorful too (especially when they are a schooling species). Create quite a vibrant show for you to watch!

Glowlight Tetra care

The light tetra is pretty easy going, especially when compared to many other popular fish. They are surprisingly hardy and can tolerate a wide range of conditions. Like many other types of tetra species, they make excellent pets for beginners.

With all of that said, there are still some important care guidelines you’ll need to follow. Adhering to these recommendations will result in healthier, more vibrant fish.

tank size

Thanks to their small size, glow tetras don’t need a huge tank. You can keep half a dozen fish in a standard 10 gallon tank!

However, we recommend increasing the tank size up to 20 gallons or more if possible. With a larger tank, you can keep a sizeable group while still providing plenty of room to roam. These fish are most comfortable when living in large groups, so larger tanks are always an advantage.

water parameters

The goal of any fish should be to mimic its natural environment in captivity. Glowlight tetras come primarily from the Essequibo River, the longest river in Guyana. A tank with similar water conditions is best.

In the Essequibo River, the waters are dark. This is because the remains of fallen leaves in the water release tannins, which makes the water soft and slightly acidic.

Hemigrammus erythrozonus tetras can tolerate a wider range of conditions than most species, but here are some basic parameters to stick to:

  • Water temperature: 74°F to 82°F (around 77 is ideal)
  • pH levels: 5.5 to 7.5 (try to keep it on the acidic side)
  • Water hardness: up to 15 dGH

Author’s Note: To monitor these parameters and ensure no changes are necessary, it is important to purchase a reliable water testing kit. We recommend choosing a high-quality one (although they tend to be more expensive) because they will provide you with much more accurate information.

What to put in your tank

Simple and natural decoration is the best for your light tetra! At the bottom of the tank, create a thin layer of substrate with fine sand. This sand will mimic the riverbeds of its wild habitat.

Next, add pieces of driftwood and small rocks. These decorative elements provide some enrichment while also giving these fish places to hide.

Finally, add a wide variety of plants. You want the tank to be full of vegetation! Add some fine-leaved plants of varying heights. Floating aquarium plants are also good.

Author’s Note: When placing the plants, make sure there is still some free space for swimming in the center of the tank. Plants are important, but so is keeping the aquarium open.

If you want to go the extra mile, you can even put some leaf litter in the bottom of the tank. The sand will produce tannins over time as it breaks down. Some aquarists will place a small bag of aquarium-grade peat moss in the filtration system to infuse the water with healthy tannins.

Common Potential Diseases of Hemigrammus erythrozonus

Light Tetras are not at higher risk for disease than any other species, and they don’t have any species-specific ailments to watch out for. However, they can suffer from all of the common health problems that affect freshwater fish.

The most common include parasitic infections, bacterial infections, fungal diseases, and fin rot.

The most widespread fish disease is ich. It is a parasitic condition that results in the formation of white spots all over the body. Ich is highly contagious and potentially lethal. If you notice one of your Hemigrammus erythrozonus tetras suffering from the disease, you should quarantine and treat it as soon as possible.

This is a smart practice for all other diseases as well. In a closed environment like a fish tank, diseases have the potential to spread and wipe out an entire community.

Fortunately, most health problems can be avoided with proper tank maintenance. Stay aware of water conditions and test the environment regularly. With regular water changes, you should have no problem keeping the habitat in good condition.

Food and Diet

Glowlight tetras are omnivores. They will eat almost anything. However, the trick is to find something that you can actually put in your mouth!

It is best to follow a standard diet of micropellets or small flakes. You can also provide an occasional high-protein snack. Freshly hatched brine shrimp and small pieces of freeze-dried tubifex are good choices.

Feed these fish several times throughout the day, but keep meals light. Only provide enough food that they can consume in a couple of minutes.

Author’s Note: Most glow tetras will not venture to the bottom of the tank to eat leftover food, so be careful not to overfeed them (this can lead to a rapid decline in water quality).

behavior and temperament

Glowlight tetras are very calm and calm. They are school fish, so they prefer to be in groups of their own kind. At the very least, you should have at least six Light Tetras (although more is always better).

When a Hemigrammus erythrozonus tetra is alone or in a very small group, they can become nervous. They will spend most of their time hiding instead of adorning their tank with color. But in a large group, they feel safe enough to go around the tank.

You will usually see your tetras huddle together and explore the tank together no matter what time it is. This is one of the main reasons why they are such a popular species for owners who enjoy watching their fish.

Aggression is not a big problem. In fact, glowlight tetras will even leave slow-moving fish or those with flowing fins alone. They are large community fish that pay no attention to others.

tank mates

Speaking of community fish, you have a lot of great options for glow tetra tank mates! Thanks to their docile nature, these fish can coexist with most species.

That said, you should avoid any aggressive or large fish. While the bright lights won’t bother larger fish, they can quickly become food for predators. This is especially true with angelfish! Angels are known to eat luminous tetras.

Keep things quiet and look for species that are similar in size. Some good tankmates for the luminous tetra include:

  • Other peaceful tetras
  • cory catfish
  • Picks (we like the cherry pick)
  • guppies
  • Docile loaches (kuhli and clown are our favorites)
  • molly fish
  • danios
  • Most gouramis (try honey or sparkling gourami)
  • Pacific bottom feeders

Light Tetra Breeding

Luminous tetras are more than capable of reproducing in captivity. But the process is a bit more challenging than that of other species. These fish can be picky about spawning conditions. Also, eggs are very sensitive to light!

It is important to create a separate breeding tank before you begin. Fill it with fine-leaved plants and spawning mops. They will keep the eggs protected.

Soften the water. Hardness indices should not exceed 6 dGH. To increase your chances of inducing spawning, use peat moss to darken the water.

Author’s Note: To prepare your fish for breeding, condition them with high-protein feeds several times a day.

When you’re ready, turn off the lights in the rearing tank and add your fish. Then gradually increase the lighting until spawning occurs. The adult fish will go through their mating ritual until the female releases 100 to 150 eggs.

Remove adults immediately after eggs are released. Glowlight tetras do not care for the eggs. Instead, they may try to eat them.

The eggs are extremely light sensitive, so keep the lights low in the breeding tank. The eggs hatch in one day. At that time, the fry will live in their egg sacs for another couple of days.

When they are free swimming, provide infusoria and finely crushed flake food. You can also move on to newly hatched brine shrimp once they are large enough.


The light tetra is something that almost anyone can handle. These fish are quite hardy and easy to keep.

When you combine that with their stunning appearance and active personality, it’s no wonder why they make such good freshwater fish to keep in an aquarium. We heard from other owners and readers who absolutely love this species!

We’re more than happy to help if you have additional questions, so don’t hesitate to contact us. And if you just want to say hello, that’s fine too!

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