Glowlight Tetra
(Hemigrammus erythrozonus)

Glowlight tetras or Hemigrammus erythrozonus are native to the Essiquibo basin in South America. Glowlights like all tetra are a member of family Characidae. They received the name glowlight tetra because of the highly reflective red stripe that runs from their mid-body to their tails. This stripe appears to glow under aquarium lighting.

Tetras are shoaling fish. Shoaling fish are extremely social fish that instinctively travel in a group. They tend not to fare well in an aquarium devoid of other members of their species. Depending on how strong the instinct runs in an individual species, some shoaling fish can not survive at all in an isolated environment. It is always advisable to have at least four of any given shoaling fish in a community fish tank.

The glowlight tetra is a small freshwater fish variety, reaching an adult length of only about an inch and a half. They have a mild disposition and make wonderful additions to community tanks provide they are in the presence of similarly natured fish whose size is not big enough to view them as a source of nutrition.

Glowlights, like all tetras, are hiders. They take readily to heavily planted aquariums. Giving them plenty of places to hide will increase these rather small fishes’ chances of long-term survival in a community setting. Glowlights are mid-tanks swimmers. So you want vegetation large enough to be present in the middle of your aquarium.

Most freshwater species native to South America thrive in slightly acidic water. Glowlights are no exception. Glowlights are accustomed to a pH level of around 6.8 with a water temperature between 75-83 °F.

Tetras are omnivores by nature. They can survive perfectly well on a diet of garden variety tropical fish food flakes. They will also eat frozen and freeze dried products and live food such as brine shrimp.

Male and female glowlights have an identical color palette. You can generally distinguish between sexes by the shape of their bodies. Female have a fuller, more rounded body than males. This trait is more pronounced when they are carrying eggs.


Glowlight tetras are more apt to breed in an environment that closely mimics their native waters. Filtering the aquarium water through peat or adding a thin layer to the substrate will help make them feel at home and help to induce breeding.  Make sure the peat doesn’t contain chemical additives or fertilizers. A breeding tank should always be used. Provide the tank with plenty of fine leafed foliage. Hornwort will work well for this purpose.

The glowlight tetra is an egg layer. Egg layers are notorious for eating their un-hatched eggs. Tetras will scatter their eggs among the plants instinctively. Promptly remove the adults from the breeding tank after spawning.  The fry will be much more likely to survive without the adults present.

Fry will hatch in about 24 hours. Newly hatched fry can be feed a liquid fry food formulated for egg laying fish. In a few days their diet can be switched over to newly hatched brine shrimp. Powdered eggs are an acceptable substitute. In a week or so they can be fed finely crushed tropical fish flakes.