Glowlight Tetra 101: Care, Tank Mates, Breeding & More

The glowlight tetras is one of our favorite freshwater species. They’re 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’re a great choice for beginners or experienced owners who want a low-maintenance fish to care for.

This guide goes over the glowlight tetra care in complete detail. You’ll learn about their diet, tank mates, lifespan, 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 the world over. Take one look at this beauty and it’s not hard to see why!

A shoal of glowlight tetras

Because these are such colorful fish, they can really liven up the appearance of any freshwater aquarium. As a shoaling species, glowlight tetras regularly group up and dart around the tank to create an eye-catching display of color.

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

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The glowlight tetra has a torpedo-shaped body. At first glance, it looks very similar to its more popular cousins, the neon tetra and cardinal tetra.

However, most of the body is semi-transparent. It takes on a silvery base color that you can see right through. This becomes quite apparent when you look at them up close.

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

A glowlight tetra in a moderately planted tank

Author Note: The stripe looks like the filament of a light bulb, which is how this species got its common name.

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

One cool thing about this stripe is that it even crosses 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.

Differences between male and female glowlight tetras are subtle. Females are typically a bit larger and feature a plumper body shape.


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

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

Author Note: Purchasing your fish from a trustworthy seller will also improve the chance that they enjoy a long lifespan. Do your homework!

Average Size

The typical size of a glowlight tetra is around 1.5 inches in length when fully grown. These are tiny creatures, making them a great fish for nano tanks.

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

We always enjoy it when small fish like this are also colorful (especially when they’re a shoaling species). It creates quite a vibrant show for you to watch!

Glowlight Tetra Care

Glowlight tetra care is really quite easy, especially compared to many other popular fish. They’re surprisingly hardy and can tolerate a wide range of conditions. Like many other types of tetra species, they make great pets for first-timers.

All that said, there are still some important care guidelines you’ll have to follow. Sticking to these recommendations will result in healthier and more vibrant fish.

Tank Size

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

However, we recommend increasing that tank size up to 20 gallons or more if possible. With a larger tank, you can keep a sizable group while still providing plenty of space to roam. These fish are most comfortable when living in big groups, so bigger tanks are always a plus.

Water Parameters

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

In the Rio Essequibo, the waters are dark. That’s because the fallen leaf debris in the water releases tannins, which makes the water soft and slightly acidic.

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

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

Author Note: In order to monitor these parameters and ensure that no changes need to be made, it’s important to pick up a reliable water test kit. We recommend picking up a high-quality one (even though they tend to be more expensive) because they will provide you with far more accurate information.

What To Put In Their Tank

Simple and natural decor is best for your glowlight tetra! On the bottom of the tank, create a thin layer of substrate with fine sand. This sand will mimic the riverbeds of their wild habitat.

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

Finally, add a wide variety of plants. You want to make the tank lush with vegetation! Add some fine-leafed plants of varying heights. Floating aquarium plants are good, too.

Author Note: When you arrange the plants, make sure there is still some free swimming space 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 place some leaf litter at the bottom of the tank. The litter will produce tannins over time as it decays. Some aquarists will place a small bag of aquarium-safe peat into the filtration system to infuse the water with healthy tannins.

Common Potential Diseases

Glowlight tetras are at no higher risk of experiencing disease than any other species, and they don’t have any species-specific ailments that you need to watch out for. However, they can suffer from all of the common health issues that impact freshwater fish..

One glowlight tetra looking for food in a freshwater aquarium

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

The most widespread fish disease is ich. It’s a parasitic condition that results in white spots forming all over the body. Ich is highly contagious and potentially lethal. If you notice one of your glowlight tetras suffering from the disease, you need to quarantine them and provide treatment 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 are avoidable with proper tank maintenance. Stay on top of water conditions and test the environment regularly. With regular water changes, you should have no problem keeping the habitat in good shape.

Food & Diet

Glowlight tetras are omnivores. They will eat just about anything. However, the trick is finding something they can actually fit into their mouths!

It’s best to stick with a standard diet of micropellets or small flakes. You can provide the occasional high-protein snack as well. Freshly-hatched brine shrimp and small pieces of freeze-dried tubifex are good options.

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

Author Note: Most glowlight tetras aren’t going to venture to the bottom of the tank to eat leftover food, so be cautious not to overfeed them (this can lead to a rapid decrease in water quality).

Behavior & Temperament

Glowlight tetras are very peaceful and easy-going. They are shoaling fish, so they prefer to be in groups of their own kind. At the very least, you should have at least six glowlight tetras (although more is always better).

When a glowlight tetra is alone or in a very small group, they can grow skittish. They’ll spend most of their time in hiding rather than adorning your tank with color. But in a large group, they feel confident enough to zip around the tank.

You will usually see your tetras grouping up and exploring the tank together no matter what time it is. This is one of the main reasons why they’re such a popular species for owners who enjoy observing their fish.

Aggression isn’t a huge problem. In fact, glowlight tetras will even leave slow-moving fish or those with flowing fins alone. They are great community fish that will pay no attention to others.

Tank Mates

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

Hemigrammus erythrozonus swimming together

With that being said, you should avoid any aggressive or large fish. While the glowlights won’t bother bigger fish, they can quickly become food for predators. This is especially true with angelfish! Angels are notorious for eating glowlight tetras.

Keep things peaceful and go for species that are similar in size. Some good glowlight tetra tank mates include:

Glowlight Tetra Breeding

Glowlight tetras are more than capable of breeding in captivity. But, the process is a bit more challenging than other species. These fish can be picky about spawning conditions. Plus, the eggs are highly sensitive to light!

It’s important to create a separate breedings tank before you get started. Fill it will fine-leafed plants and spawning mops. They will keep the eggs protected.

Make the water very soft. Hardness ratings should be no higher than 6 dGH. To increase your chances of inducing spawning, use peat to darken the water.

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

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

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

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

When they are free-swimming, provide infusoria and finely-crushed flake food. You can also move onto freshly-hatched brine shrimp once they are big enough.            


Glowlight tetra care is something that pretty much anyone can handle. These fish are quite hardy and easy to keep.

When you combine that with their stunning looks and active personality, it’s no wonder why they’re such a great freshwater fish for keeping in an aquarium. We hear from other owners and readers who absolutely love this species!

We’re more than happy to help you out if you have additional questions, so feel free to reach out. And if you just want to say hi, that’s fine too!

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