Glowlight Tetra (Hemigrammus erythrozonus): Ultimate Care Guide

Common NameGlowlight Tetra
Scientific NameHemigrammus Erythrozonus
OriginGuyana, South America
Temperature74F – 82F
Water pH5.8 – 7.5
Sizeup to 2 inches

Glowlight Tetra Facts

  • As their name suggests, Glowlight Tetras do glow. This glowing effect can be seen much better when lighting is kept dim, or Glowlight Tetras are kept in a small group.
  • Glowlight Tetras were introduced into the aquarium trade in 1933.
  • Glowlight Tetras provide no parental care to their offspring, so parent fish must be removed from their breeding tank to ensure that they do not cannibalize their own offspring.
  • Glowlight Tetra eggs also glow, but they are light sensitive. They need to be protected by dim lighting.

Glowlight Tetra

Glowlight Tetras can be identified by their silvery, torpedo shaped bodies and bold, iridescent, orangish-red stripes that run along the length of their bodies. This stripe resembles the filament in a light bulb, and it is slightly reflective. Glowlight Tetra dorsal fins also sport the exact same colorings at their base as the stripe on their bodies. The color fades to an iridescent looking silver as it gets to the tip of the dorsal fin.

The main feature of the Glowlight Tetra is their glowing feature. This is more easily seen when lighting conditions are kept dim, and they are kept in a group. Glowlight Tetras are a shoaling species, and when they are together in a group, it makes it much easier to see their glowing effect.

Glowlight Tetra
Glowlight Tetra (Hemigrammus erythrozonus)

Male and Female Glowlight Tetra

Determining the difference between male and female Glowlight Tetras is much the same as determining the difference in sex between other Tetras. The females tend to be larger and more rounded when viewed from the top. It is much easier to tell the difference between males and females when they reach sexual maturity. Females will be the roundest when they are ready to spawn and full of eggs. It is at this point, if you are planning on breeding Glowlight Tetras, that you move your breeding pair into a separate breeding tank.

Do Glowlight Tetra Glow in the Dark?

Glowlight Tetra are a popularly kept fish in home aquariums due to the glow effect that they possess. The Glowlight Tetra can be seen glowing when kept in the right lighting conditions. This glowing effect can be better seen if their aquarium lights are dimmed and heavily planted. Keeping a group of Glowlight Tetras together will also make their glow more visible. Glowlight Tetra eggs also emit a faint glow that is better seen when lighting is dim.

Tank Size and Requirements

Glowlight Tetra are a shoaling species, and this means that they need to be kept in a small group. This will help them feel comfortable enough to show off their unique personalities and shoaling behaviors.

Glowlight Tetra require a minimum of a 10 gallon tank to house up to 6 Glowlight Tetra, however if you can provide them with more space, it is largely beneficial. A 20 gallon, for example, would give them much more space to roam, and allow for more Glowlight Tetras to be kept together.

Glowlight Tetra are a tropical fish, and this means that they prefer warmer waters. They need to be kept at around 74F to 82F and 5.8 to 7.5 pH.

This also means that Glowlight Tetras will need a quality heater. Even though Glowlight Tetras are a hardy fish, they are still susceptible to ailment if they are not kept in the right conditions. You will want to monitor their water parameters often to make sure that you catch any problems before they affect the fish.

Tank Setup

When setting up a tank for Glowlight Tetras, you will want to keep in mind the way they live in their habitat in the wild. Glowlight Tetras inhabit low light, brackish waters and streams of South America. The waterways they inhabit are littered with leaves and debris from the trees and plants around them. This decaying plant matter releases beneficial tannins into the water for Glowlight Tetra as well as providing them with a source of food. You can purchase leaves for your home aquarium that will provide them with the same nutrients.

Choosing a dark substrate and many plants will help your Glowlight Tetras feel more at home. They prefer their aquariums to be heavily planted, but you will need to be sure to give them enough space to roam as well. Floating plants are another good option to help give them the shade they require as well as helping to keep their lighting dim.

Food and Diet

In the wild, Glowlight Tetras are omnivorous, opportunistic feeders that will feed on plant and animal matter if it is readily available. They will often eat the decaying leaves that are at the bottom, algae, larvae, and even tiny invertebrates.

In captivity, you can expect Glowlight Tetra to eat flakes, freeze dried, frozen, and even live foods. It is important to make sure that the foods you are offering your Glowlight Tetra are small enough to fit in their mouths. This can be a challenge as they are such small fish. Make sure that you observe them during feeding time to see if they are able to eat what you are giving them. It is better to feed these fish two small meals a day opposed to one large one, and only feed them enough food that they can completely consume in 2 to 3 minutes as this helps cut down on waste material in their tank.

Size and Lifespan

Glowlight Tetras have an average lifespan of 2 to 4 years when kept in captivity. This is a slightly shorter lifespan than other Tetras. At full maturity the Glowlight Tetra will still be roughly 1.5 to 2 inches. Their lifespan is greatly dependent on the conditions in which they are kept. If they are properly cared for they can potentially live longer.

Are Glowlight Tetras Aggressive?

Glowlight Tetras are not an aggressive fish species, however some owners of Glowlight tetra have reported that they have come across an aggressive one of the group. This seems largely dependent on the individual fish, but not the group as a whole. You should monitor all fish when you first get them to make sure that you can correct any problems before they become an issue.

Glowlight Tetra School Size

Glowlight Tetras are a shoaling fish, and they need to be kept in a minimum school size of at least 6 in a 10 gallon tank If you can provide them with more space that is ideal as Glowlight Tetras are an active fish that likes room to dart about.

 Shoaling fish are fish that stay together as a group. They do this for social reasons. You will always see the fish in the group swimming together and in the same direction. You can keep more Glowlight Tetras if they are provided with a larger tank. The general rule is that for every 1 inch fish, you need an additional 1 gallon of water in their aquarium. 

Glowlight Tetra Tank Mates

The best tankmates for Glowlight Tetras are other Glowlight Tetra. These fish are shoaling fish, and they are most comfortable in groups as small as six and as large as you can accommodate. They are best kept with other peaceful fish such as Danios, Corys, Barbs, loaches and other types of Tetra.

Incompatible tankmates include larger, more aggressive species of fish. Since Glowlight Tetras are a more peaceful fish, it is important to pair them with other fish that have relatively the same temperament. Avoid fish that are territorial, compete for resources, or are fin nipping such as Gouramis.

Glowlight Tetra and Betta

Glowlight Tetras and Bettas can be housed together safely as long as they are provided with enough space and fed correctly. Betta fish are carnivorous and Glowlight Tetra are omnivorous. This could lead to problems at feeding time, and in their diet. If you are planning on putting Glowlight Tetras and Betta fish together, it is advised that you provide them with a tank that is at least 20 gallons and heavily planted.

Glowlight Tetra and Angelfish

Glowlight Tetras are typically wonderful fish to include in a community setup that has slow moving fish with flowing, long fins. However, Angelfish are not a good tank mate for Glowlight Tetra as they will see the Glowlight Tetra as food and eat them.

Glowlight Tetra and Guppies

Guppies are excellent tank mates for Glowlight Tetra, and they can be housed in a community setup safely together as long as their needs are being met. It is important when introducing new fish together that you observe their behaviors. By observing the fish together you will be able to correct any problems as they arise.

Glowlight Tetra Breeding

If you are planning on breeding Glowlight Tetra, you will want to consider setting them up with a dedicated breeding tank. This will ensure your success at breeding Glowlight Tetras and survival of the Glowlight Tetra fry. The setup of a Glowlight Tetra breeding tank is much the same as the setup of their main aquarium. You will want to make sure that your Glowlight Tetra breeding tank is heavily planted with floating plants to provide them with as much cover as possible.

When Glowlight Tetras are ready to spawn, you will be able to see the male and the female lock together and both release their genetic material at the same time. The female Glowlight Tetra will release anywhere from 60 to 130 eggs. Glowlight Tetra eggs take around 24 hours to hatch. Once you notice that the parent fish are done spawning, it is advisable to remove them from the breeding tank so that they do not cannibalize their own offspring.

Glowlight Tetra Eggs

You will be able to visibly see if your female Glowlight Tetra is ready to spawn. Her abdomen will swell and this is an indicator that she is full of eggs. In fact, seeing the female Glowlight Tetra full of eggs is the easiest way to determine if you have a male or a female Glowlight Tetra. Glowlight Tetra eggs are sensitive to bright lighting, so it is integral that they remain in a low light aquarium.

Glowlight Tetra Disease

Glowlight Tetra are considered a hardy fish and are fairly resistant to most ailments. Glowlight Tetra can be infected with most of the same illnesses as other freshwater fish, and if they are kept in less than adequate conditions they can develop severe problems.

Glowlight Tetra can be affected by bacterial, fungal, and bacterial diseases. Glowlight Tetra can also acquire Neon Tetra Disease. This disease is a quick spreading, and oftentimes devastating illness that affects Tetras specifically. There is no known cause of this ailment in Tetras, and no real cure.

The best way to protect your fish and their longevity is to provide them with the appropriate setup and water parameters. If Glowlight Tetra are not cared for properly they will become stressed, and stressed fish will quickly become ill.

Where Can I Find Glowlight Tetra for Sale?

If you are looking to purchase Glowlight Tetra for your home aquarium, you will be able to find them for purchase at some pet stores and from breeders online. You will want to make sure that you are purchasing your fish from a reputable source to ensure that the fish you receive are healthy and ailment free.

Glowlight Tetra vs Neon Tetra

Glowlight Tetra and Neon Tetra are very similar fish in all aspects except their markings and coloration. Neon Tetras do not glow, and they have bright, electric blue stripes that run along the length of their bodies instead of the vibrant red that Glowlight Tetras have. These fish are compatible together for a community setup, but even though they are shoaling fish, they will not shoal together.