Hemigrammus erythrozonus (Glow-light tetra)

Hemigrammus erythrozonus which is also known as the Glow-light tetra belongs to the Characidae family and Characiformes order. The species may also be known as Hyphessobrycon gracilis.
The species is native to South America (Guiana). The Glow-light tetra occurs in flooded forests and tributaries of the Essequibo river. The water conditions are low in minerals and nutrients and rich in tannins due to the decomposition of organic matter such as woods and leaves (an indication of soft and acidic habitat). Furthermore, the species live in dark areas with very little sunlight all the time.
Glow-light tetra has a thin, translucent-silver body with an orange-red line that extends from the head to the tail. There is also a red spot above the eye. Furthermore, male Glow-light tetras are thinner while mature female Glow-light tetras have round abdomens. The species grow up to 4 cm and have a lifespan of 4 years.
In contradiction from many other tetras, the glowlight tetra is an excellent choice for beginners because of his hardiness and easiness of reproduction. Like the al the tetras, Hemigrammus erythrozonus are shoaling fish that should be kept in groups of 6 individuals and more. They are also suited for community tanks with peaceful species with a similar size and water chemistry. Some compatible species are corydoras and other peaceful tetras.
Because of the natural habitat of Glow-light tetra, they should be kept in soft acidic water. You may decorate the aquarium with, rocks, leaves, and woods to create the biotope of Hemigrammus erythrozonus for a more original look. However, a densely planted tank has many benefits and gives a stunning appearance with the Glow-light tetras’ color. A pH between 5.5-7.5, with a temperature between 24-28 Celsius, and hardness between 5-12 dH, suits the species.
An aquarium of 65 liters could be enough for a group of 6-8 Glow-light tetras. However, a bigger school of the species in a larger tank would be much better.
Glow-light tetras are omnivorous and can eat prepared food and small live-foods. In nature, their diet consists of crustaceans, insects’ larvae, worms, and plant matter, e.t.c.
Glow-light tetras are egg scatterers and quite easy to breed. They reproduce better at 26-28 Celcius, 5,5-6,5 pH. You may cover the tank to create darkness with papers or other materials because tetras’ eggs and fry are sensitive to daylight. After twelve days the young are not susceptible to the light. A mixed diet with live food prior spawning attempt may help. Woods and leaves (almond leaves) benefit the process as they provide tannins and humic acids. The tank needs good aeration for the optimal health of the eggs. An air-powered sponge filter does the work. You may use a breeding tank of 40 liters (10 gallons) with 15 cm of water depth for better results for a pair or three females with three males in the tank.
Replace the individuals if no eggs have appeared for 2-3 days. Remove the adults If the spawning is successful to protect the eggs. Furthermore, you may cover the bottom of the tank with a net to protect the eggs from the adults. The female lays about 50-150 eggs, which hatch in about 24-36 hours. Keep in mind that the temperature affects the eggs’ hatching period. For 3-5 days the young feed on the yolk sac, so in that period they don’t need food. After the consumption of the yolk sac, you can feed the young three times per day with infusoria and zooplankton until they get bigger to consume other types of food.

Glowlight Tetras in an aquarium


  1. David Alderton 2005, 2008, Encyclopedia of aquarium and pond fish, Published in the United States by DK Publishing, ISBN 978-0-7566-3678-4
  2. Hemigrammus erythrozonus. Retrieved from https://www.seriouslyfish.com/species/hemigrammus-erythrozonus/
  3. U.S. Fish and Wildlife Service, 2018, Glowlight Tetra (Hemigrammus erythrozonus). Retrieved from https://www.fws.gov/fisheries/ans/erss/uncertainrisk/ERSS-Hemigrammus-erythrozonus-final-July2018.pdf

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