Glowlight Tetra – A Bright Little Fish

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Glowlight tetras are striking little fish that are easy to care for and enjoy life in a school of their friends.

They are native to South America and are not overly fussy in terms of aquarium parameters.

Are you interested in adding these to your setup, or already have glowlight tetras and want to make sure you’re caring for them as best you can?

Then keep on reading!

Origin and Natural Habitat

Glowlight tetras were first found in the Essequibo basin in Guyana, South America.

They have also been found in the Essequibo, Potaro, and Mazaruni rivers.

Glowlight tetra’s original scientific name was Hemigrammus gracilis but that was later changed to Hemigrammus erythrozonus.

These fish first came available on the aquarium market in 1933. They have been around for a long time!

Appearance and Size

Glowlight tetras are small and narrow, reaching only an inch and a half when fully grown.

Their bodies are translucent with a peachy/silver colored body strikingly separated by a red stripe that runs along the entire fish.

Glowlight tetras get their name from the stripe since it looks like a glowing lightbulb.

That red color extends to the edge of their dorsal fin.

Their anal and pelvic fins are white-lined.

This unique red line sometimes leads to glowlight tetras being mistaken for glowlight rasboras, who also have a red line in the middle of their body.

You can tell the difference by looking at the adipose fin, or lack thereof in the rasbora’s case.

Diet for Glowlight Tetra


On average, glowlight tetras live from two to four years with good care.

They do not like poor water conditions or bad diets, but that doesn’t mean they are hard to care for.

Follow the tips below for a detailed guide on how best to care for your glowlight tetras.

Tank Size and Setup

Glowlight tetras are small fish which means they don’t need a massive tank.

Six of them can quite happily fit in a 10-gallon tank, but if you want a bigger school, try and up that to 20 gallons.

The larger size tanks give you more room to play in terms of decorations and tank mates.

Glowlight tetras enjoy living in big schools, so a bigger tank plus more companions equals happy glowlights!

Keep it simple when decorating, and think naturally.

For the substrate, a fine sand works well. This will mimic their native riverbeds. Decorations like driftwood and rocks will make for happy glowlight tetras and feel free to add lots of plants.

They will love a tank with thick vegetation.

The rivers that wild glowlight tetras live in are rich in tannins, which is the product of the water being full of leaf litter and plant matter.

Tannin rich water has a brownish tinge, mimicking wild water ways. You can buy leaf litter for your tank that will produce tannins as it decays.

This is another nice addition to make your glowlight tetras feel at home.

how to breed glowlight tetras

Water Parameters

Keeping your water parameters closest to the fish’s natural habitat is the main priority.

The waters in the Essequibo river are dark due to the rich tannin content. This makes the water slightly acidic and soft.

Glowlights aren’t overly sensitive to their water conditions but you should keep the temperature around 77°F, the pH from 5.5 to 7.5, and the water hardness no higher than 15 dGH.


Glowlights are generally quite easy to care for compared to other fish.

They are fairly hardy and don’t have a melt down when the water conditions change but that doesn’t mean you should constantly be adjusting your water parameters.

Fish like consistency and frequent water shifts can stress them out.

Like most tetras, glowlight tetras are a good choice for beginner fish keepers.

Even though a fish is hardy, doesn’t mean that they can be neglected. Make sure to follow the guidelines laid out in this blog post to keep your glowlight tetra in tip top shape.

Temperament and Behavior

Glowlight tetras are lovers, not fighters.

They have peaceful temperaments and have an easy nature that loves living with fellow glowlights.

To keep them happy, and fulfill their shoaling wishes, you must keep at least six glowlight tetras in a tank.

If you have enough space for more, then add more!

A big group of glowlight tetras make a beautiful feature in a tank, especially with them darting in and out of the vegetation and schooling together in the open spaces.

Glowlight tetras that are kept alone can grow timid and spend time hiding, rather than exploring the tank and feeling safe to be out in the open.

They are very entertaining fish to watch when they are in a group.

Care Glowlight Tetra

Tank Mates

Glowlight tetras are not aggressive and can be housed with slow moving fish.

They are not known fin nippers and are perfect community fish. If you want to keep things simple, a big group of glowlights work great together without the need of adding other fish.

If you want some additional shapes and colors, consider one of the following; cory catfish, most other small tetras (like the neon and cardinal), and danios.

Glowlight tetras are unlikely to school with other types of fish, they need at least 5 others of their own kind to create their little shoal.

One thing to keep in mind is steering clear from any aggressive fish or fish that are super active and dart aroubd the tank. These will stress out the chilled glowlight tetras.


Glowlight tetras are omnivores and will eat a variety of food.

A quality pellet or flake is a good base for them, and you can add some variety through things like brine shrimp and blood worms.

Do not feed your glowlight tetras too much. They are not usually bottom feeders and often don’t pick up fallen flakes or pellets.


Glowlight tetras are generally hardy fish that are not prone to disease.

They can, however, suffer from common health issues that face all freshwater fish species. These include fin rot, parasitic and bacterial infections, and fungal diseases.

Ich is the most common fungal disease which sees the fish forming white spots over their body.

Ich is high contagious and can be deadly if not treated quickly. Once you notice any changes to your fish and suspect ich is the cause, quarantine the fish and begin treating them.

Your best defence against any diseases or infections is proper care.

Focus on good feeding, correct water parameters, and low stress.

That will give you glowlight tetras the best defense against any nasty illnesses!

Glowlight Tetra tank mates

Sexing and Breeding

Female glowlight tetras have larger bodies and appear rounder than the males.

Males are smaller and more slender. Their colors are the same.

Breeding glowlight tetras is not the easiest thing in the world. It can be done but they are known to be finicky.

If you want to attempt it, do the following.

Prepare a separate breeding tank with very soft water. It mustn’t be any higher than 6 gDH and have pH from 5.5 to 7.0.

Keep the temperature warmer than usual, around 78 to 82 F. Keep aquarium lights off and choose plants like java moss.

Choose a female in the best condition, she needs to be plump for breeding.

You can do this by feeding small meals often with live foods included. Make sure to not over feed your fish though, this can have dire consequences.

Once a female is round, place her in the breeding tank with a male.

Once they are ready to spawn, the male will perform a courtship ritual.

When glowlight tetras spawn, 100 to 150 eggs will be produced.

They are not needed to parent the fry and will eat the eggs. Once they have spawned, remove both parents from the tank.

Do not put bright lights over the tank! Eggs are very light sensitive and need to be in the dark.

Fry will hatch in 4 hours and by 3 days old, they will be swimming around the tank.

Newly hatched fry must be fed infusoria which can then be changed to fine powder or crushed flakes when they are a few days old.

Should you add this fish to your tank?

Glowlight tetras are easy, calm tempered fish that make good beginner fish.

They are fairly hardy and suit community tank living.

Make sure to keep at least 6 together in a tank so they can shoal together and feel free to decorate their tank with natural features.


Are glowlight tetras aggressive?

No, these tetras are very peaceful.

Are glowlight tetras fin nippers?

No, glowlight tetras are not fin nippers.

Are glowlight tetras neon tetras?

No, they are not. Neon tetras are a totally separate species.

How many glowlight tetras should be kept together?

These fish love to be in big groups so the absolute minimum is 6 individuals in a tank but go bigger if you can.

How long do glowlight Tetra live?

Some individuals can live up to 6 years but it is more common for them to live anywhere between 2 to 4 years.

How often should I feed my glowlight tetras?

If your fish are young then the recommendation is twice a day. My fish are adults so I only feed them once a day.

Check out all these different types of freshwater fish.

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Irma Bense is the founder of She has over 42 years of experience in keeping fish.She has kept both freshwater and saltwater fish through the years.She has extensive knowledge in breeding numerous species of fish from Show Guppies, Cory Catfish, German Blue Rams to Apistogrammas.You can learn more about Irma on the 'About' page.

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