Glowlight tetra care guide

Glowlight tetraa (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 habitat is in the North of South America (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.

Scientific NameHemigrammus erythrozonus
Common NamesGlowlight tetra; glow tetra; glolite tetra
Range and habitatSouth America
Size4-5 cm (1.6-2 inches)
Lifespan3 years
Ease of keepingMedium
Minimum tank size15 gallons (70 litres)
Temperature22° – 28° °C (72° – 82 °F)
Water hardness5-20 dGH


Glowlight tetra is one of small and slim tetra species. Max size is up to 5 cm (2 in) and its lifespan in the tank is about 3 years.

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.

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 6-7 species, therefore they require a tank of 12 gallons capacity and more. When keeping any kind of tetra the lights should be dim and soft. The best way to meet this requirement is to put some fluctuants into the tank.

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 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. The proper water parameters are: temperature 22-28 C, ph: 6.0 – 7.5 , 2 – 15 dGH.

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.

Compatibility and 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.

The majority of live-bearing fish (guppies, platy, swordtail, molly), harlequin rasbora, white cloud mountain minnow and other tetra species, corydoras and loricariids can be tank mates.

However, larger fishes such as cichlids aren’t safe tank mates, since they’ll consider the glowlight tetra as feed.

Gender differences: male vs female

Glowlight tetra females are larger and fatter than males, which are in turn more slim and colorful.


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.