Glowlight Tetras Made Easy: Simple Care Guide for Beginners

Glowlight tetra (Hemigrammus erythrozonus) are small tank fishes of Tetra family, which have a nice glowing stripe along their body. A school of these fishes can impress even an experienced and skilled aquarist. With aging the fish body color becomes more and more saturated and the fish becomes more good looking.

Habitat in the wild

Glowlight Tetra, also known as Hemigrammus erythrozonus, is a small and peaceful tropical fish that belongs to the Characidae family. The Characidae family is a diverse group of freshwater fish that includes various species of tetras. Tetras are known for their vibrant colors, schooling behavior, and peaceful nature. They are native to South America, primarily found in rivers and streams of the Amazon basin.

Glowlight tetras are native to the tropical rainforests of South America, specifically the Amazon River basin (Guyana, Suriname). The fish lives in small rivers with turfy bottom and towering trees on their shores. Very little sunlight gets into the water through thick leaves, so there is twilight there all the time.

The water is brownish due to turf and humic acids that are produced by rotting leaves, all these additionally decreases the water transparency. Blackwaters saturated with humic acids also have the following peculiarity – their water is almost completely free from any bacterias – i.e. it’s almost aseptic – it has acidic active water response (pH), about 6.0–6.5.

Almost complete absence of calcium in the turfy bottom covered with leaves results in a very low level of water hardness (gH 1–3, KH 0–0,1). Therefore, the lack of sunlight in the habitat has lead to the fact, that tetra eggs and larva almost can’t stand the sunlight.


Glowlight tetras have a slender, elongated body shape. They are streamlined and well-suited for swift movement in the water. Glowlight Tetras have relatively large and round eyes, which are usually black in color. Their eyes add to their overall appearance and are often visible due to their contrasting coloration against the bright stripe.

The most striking feature of the glowlight tetra is its vibrant coloration. The base color of their body is silvery or translucent. However, the most prominent and distinguishing feature is a horizontal stripe that runs from the head to the base of the tail. This stripe is usually bright red or orange in color, hence the name “Glowlight Tetra.” The stripe appears to glow under proper lighting conditions.

The glowlight tetra is somehow alike the black neon tetra, especially in having the glowing stripe on its body, but still it’s a completely different kind. It’s easy to see between them – black neon has a black body correspondingly, and glow light tetra – has a semitransparent one.

There’s a variation called albino, but it has no differences in care compared to the ordinary fish. The albino glowlight tetra has a similar body shape and size as the regular glowlight tetra. However, it lacks the typical pigmentation seen in the species. Instead of the silver body with a red or orange stripe, the albino glowlight tetra has a translucent or pale pinkish body. It also lacks the dark pigmentation in the eyes, giving them a pink or red appearance.

How big do glowlight tetras get?

Glowlight tetra is one of small and slim tetra species. Hemigrammus erythrozonus are small fish that typically reach an average size of about 1.5 to 2 inches (3.8 to 5 centimeters) in length. It’s important to note that individual growth can vary slightly, but generally, Glowlight tetras remain within this size range throughout their lifespan. Their small size makes them suitable for smaller aquarium setups and allows for the keeping of a small school of these colorful fish.

How long do glowlight tetras live?

Glowlight tetras have an average lifespan of about 3 to 5 years under proper care and optimal conditions. However, it’s important to note that individual variations can occur, and some tetras may live shorter or longer lives.

Scientific NameHemigrammus erythrozonus
Common NameGlowlight Tetra
OriginSouth America, Amazon River basin
Size1.5 to 2 inches (3.8 to 5 centimeters)
Lifespan3 to 5 years
TemperamentPeaceful, social, schooling fish
Water Temperature75°F to 82°F (24°C to 28°C)
Water pH6.0 to 7.5
Water Hardness2 to 10 dGH
Tank SizeMinimum 10 gallons, larger tank preferred
DietOmnivorous, prefers small live and frozen foods
BehaviorActive, shoaling/swimming in groups
CompatibilityPeaceful, compatible with other small fish
Tank SetupSoft, slightly acidic water; plants, driftwood
LightingModerate to subdued lighting
BreedingEgg scatterer, requires separate breeding tank
Special ConsiderationsSensitive to poor water quality, requires clean water

Difficulties in keeping

If a tank is well balanced and set properly, it won’t be difficult to keep even for beginners. The glowlight tetra is good for those, who want to try to deal with aquarium husbandry for the first time.

Care and keeping in a tank

Tank size

Glowlight tetra feels more comfortable in a school of 6-10 species. The minimum recommended tank size for a school is 10 gallons. However, a larger tank is always preferable and provides a more stable and spacious environment for the fish.

If possible, it is advisable to provide a larger tank to promote better water quality and reduce the risk of water parameter fluctuations. A larger tank also offers more options for aquascaping, including the addition of plants, driftwood, and hiding spots, which can enhance the overall well-being of the fish.

In summary, while a minimum tank size of 10 gallons can house a small school of glowlight tetras, providing a larger tank, such as a 20-gallon or larger, will allow for better swimming space and overall tank stability, contributing to the health and happiness of your fish.

Water parameters

They aren’t demanding to the tank conditions, the main thing is that they should be reasonable and stable. Soft and acidic water is the best for tetras, but those sold where you live have already adapted to the conditions they have there.

The proper water parameters are:

  • Temperature: 75°F to 82°F (24°C to 28°C) is the ideal temperature range for glowlight tetras.
  • pH Level: Glowlight tetras prefer slightly acidic to neutral water conditions. The recommended pH range is typically between 6.0 and 7.5. It’s important to avoid extreme pH fluctuations, as they can be stressful to the fish.
  • Water Hardness: Glowlight tetras thrive in soft to moderately hard water. The recommended range for water hardness (GH) is around 2 to 10 degrees. Keeping the water on the lower end of this range is generally preferred.
  • Ammonia, Nitrite, and Nitrate Levels: The most important parameter is tank water purity and low level of ammonia and nitrates in it. To achieve these you should perform partial weekly water renew and use a filter in the tank. Ammonia and nitrite should ideally be undetectable, while nitrate levels should be kept below 20-30 ppm through regular water changes.
  • Filtration and Water Movement: A good filtration system is essential to maintain water quality and provide adequate water movement. Gentle water flow is preferred, as glowlight tetras come from slow-moving or stagnant waters in their natural habitat.
  • Acclimation: When introducing glowlight tetras to a new aquarium or when performing water changes, it’s important to acclimate them gradually to avoid temperature and pH shock. Use a slow drip or floating bag method to allow them to adjust to the new water conditions over a period of time.

Tank decor

It’s better to create some natural biotope in the tank. There should be some dark sand on the bottom, some snags and small rocks will do as tank decorations. Also you can put some leaves on the bottom, they’ll make the water a bit brownish. There aren’t so many plants in the rivers where the fish inhabits in the wild, so a thickly planted tank isn’t what it needs.


Since the glowlight tetra is omnivorous, in the tank it eagerly feeds on all types of live, frozen and artificial feed. Any types of feed – flakes, granules etc. will do.

The main thing is that the glowlight tetra should be able to swallow them. It’s better to give the fish small portions of feed 2-3 times a day, since tetra almost doesn’t eat the feed that falls on the tank bottom.

The fish will eagerly eat everything you’ll feed it with. To keep the glowlight tetra in the best of its shape and color you should feed it regularly with live and frozen feed of proper size. This can be blood worm, brine shrimp, water flea, you can also add any other artificial feed into diet.

Tank mates

Is one of the most peaceful among all tetra species. It is an active and quite colorful fish. Compatibility is quite high with the species of the same size. Although this is a schooling fish, usually it doesn’t swim in a school with other fishes. However, larger fishes such as cichlids aren’t safe tank mates, since they’ll consider the glowlight tetra as feed.

When selecting tank mates for glowlight tetras, it’s important to consider compatible species that share similar water parameter requirements and temperaments. Here are some suitable tank mates for glowlight tetras:

Gender differences: male vs female

Distinguishing between male and female glowlight tetras (Hemigrammus erythrozonus) can be a bit challenging, as the differences in appearance between the sexes are not very pronounced. However, there are a few subtle indicators that can help identify males and females:

  1. Size and Body Shape: In general, female tend to be slightly larger and plumper than males, especially when they are carrying eggs. However, this size difference may not always be easily noticeable, particularly in young or non-breeding individuals.
  2. Coloration: During the spawning period, male may display more vibrant and intense coloration, especially in the fins. They might exhibit brighter red or orange hues in their stripe and fins compared to the females. However, these color differences can be subtle and may not be consistent throughout the lifespan of the fish.
  3. Behavior: During courtship and spawning, males often display more active and aggressive behavior, chasing and courting females. This behavior may not be evident outside of the breeding period, making it difficult to differentiate based solely on behavior.

Given the subtle differences and variability in individual fish, the most reliable way to determine the sex of glowlight tetras is by observing their behavior during spawning. Females will show a plumper belly when carrying eggs, while males may exhibit more intense coloration and engage in courtship behaviors.

In a community aquarium, it’s generally recommended to keep a group of glowlight tetras rather than trying to maintain a specific ratio of males to females. This helps create a harmonious environment and allows the fish to establish their social hierarchy within the group.


You should choose the couple and put the fishes into different tanks for 5-10 days and feed them well. Keep in mind, that glowlight tetra females shouldn’t be overfed, since some cysts may appear and the fish won’t be able to breed later.

A tank of rather small capacity (about 1 gallon) will do for spawning. Put a guard grid in it and put a small bunch of tank plants on top (Thai fern or some small-leaved plants will do). Water level in a spawning tank should be about 12-15 cm, temperature 24-25 °C. The lights should be soft and dim.

The fishes require some peace, so put some sheets of dark paper on one or both sides of the tank. Prepare the water so that its resulting hardness will be not more than 4-5°, pH 6.6-6.8.

All failures in breeding are due to the spread thought that very soft water is required for it (dGH 0,5-2,0°) with acidic reaction pH 5,5-6,0 – but such water will do for breeding of Paracheirodon species.

It is different with glowlight tetra: in very soft water all seems to be good at the beginning – lots of eggs are fertilized, the embryos grow well.

However, at the later stages of their growth the troubles begin – juveniles can’t fill their fish maw with air and start jumping, rolling around the bottom and they die shortly. Let the prepared water settle for 5-6 days and only after that pour it into the spawning tank.

The glowlight tetras are usually put there in the evening. During the night they get used to the new environment and in the morning they start spawning. Sometimes it doesn’t happen at the same day and it may take a day or two.

The key factor that stimulates spawning is a natural sunrise and adding of some fresh soft and warm water (300-400 ml).

The spawning lasts about an hour or 1.5 hour. The fish lays from 50-70 to 400-450 of eggs, depending on the age and reproductive level of the breeding fishes. The eggs are small, transparent of amber-yellowish color. However, the fishes that breed for the first time have very low percentage of fertilized eggs.

Larva appear from the eggs in 25-30 hours after spawning and stay of the bottom for some time, then they stick to the tank walls. Remember, that the tank should be shaded and it needs aeration.

On the 5th day glowlight tetra juveniles start swimming. The start feed for them is infusorian. You feed the juveniles with it during the first 2 days, then you can give larger feed.

The juveniles grow rather fast. They mainly stay in the bottom water layer or under the tank plant leaves. When the juveniles become 1 month old the glowing stripe appears on their bodies and this is a crucial moment in their lives.

During this period the fish is very sensitive to all types of fungus diseases, therefore you should take care about the water purity, timely renew it and provide the fishes with stable water temperature.

At the age of 5-6 weeks the juveniles unite into schools. Glowlight tetras become reproductive at the age of 7-8 month.