Glowlight Tetra Quick Stats
Minimum Tank Size: 10 Gallons (37 Liters)
Care Level: Very Easy
Water Conditions: pH 5.5-7.5 Soft to Moderately Hard
Temperature: 74-82°F (24-28°C)
Maximum Size: 1.5 inches (4 cm)
The glowlight tetra (Hemigrammus erythrozonus) is a small tropical fish that is widely considered to be one of the best choices for a community aquarium. These fish are hardy and inexpensive and can be found in nearly every fish store around the globe.
Albino glowlight tetras are occasionally found for sale, as are golden glowlight tetras, but it’s important to note the golden glowlight tetra (Hemigrammus bellottii) is a separate species and not a color variant.
Native to Guyana, South America, these fish are found in the Essequibo River basin. However, they are rarely found in the main channel, and most of these fish inhabit the blackwaters of the tributaries – areas where the water has become stained by tannins leaching into the water from decaying vegetation. In some areas, the water is acidic and darkly stained, almost resembling tea.
The average lifespan for glowlight tetras is between two to four years, though it’s been reported that well-cared for individuals can live up to five years. They grow to a maximum size of 1.5 inches (4cm), with the females being slightly larger and plumper than the males.
Glowlight tetras make a wonderful addition to any peaceful community aquarium, and their docile nature and shoaling make them highly sought after. Because they are a shoaling fish, they should always be kept in groups of at least six, though groups of ten or more are recommended as it will help to reduce stress and make the colorful shoaling more impressive.
Currently, virtually none of the glowlight tetras for sale are wild caught and the majority are bred on commercial fish farms in Asia and Eastern Europe. Since these fish are bred on fish farms, the ones available are often high adaptable and do well in a variety of water types.
When setting up an aquarium for glowlight tetras, it should closely mimic their natural environment. A dark substrate with a layer of non-toxic leaves should be provided (a word of warning: the leaves will stain the water a light brown and will have to be replaced every few months). The top of the aquarium should be blanketed with floating plants, and driftwood or bogwood can be placed on the bottom.
Some people still recommend adding a small net full of peat to soften the water, but that’s unnecessary unless breeding is planned.
As most of these fish are kept in small to medium aquariums, it’s recommended to use a hang-on-back filter. These filters are both reliable and affordable. I personally recommend the AquaClear Power Filter, which I’ve been using for years on my aquariums without any issues.
In the wild, these fish primarily feed on insect larvae and small crustaceans. This diet can be reproduced in the home aquarium through regular feedings of a high quality prepared fish food and occasional offerings of live or frozen foods. I personally recommend Hikari Micro Pellet Tropical Fish Food, since it provides excellent nutrition and is specifically designed for small-mouthed fish.
When it comes to live foods, they will accept wingless fruit flies, mosquito larvae (illegal to culture in some areas), daphnia, blackworms (tubifex in Europe) and gut loaded brine shrimp. Their tastes are similar in frozen foods, and they can be fed frozen bloodworms, daphnia, brine shrimp, and blackworms.
Like many other tetras, the females grow larger than the males and have plumper bodies. However, it can be difficult to sex these fish before they mature, and the females fill with eggs.
Glowlight tetras are quite easy to breed, but a separate breeding tank should be set up for any significant number of fry to survive – especially if they are kept in a community fish tank. The breeding tank should be fully cycled (Read the complete guide to cycling an aquarium here), dimly lit, with soft and acidic water (Learn how to safely lower the pH here).
It’s important to provide spawning mops or finely leaved plants like Java Moss or Water Sprite for the fish to scatter their eggs in. Another option is to replace the substrate with marbles, which should allow most of the eggs to fall out of reach of the adults.
While the breeding tank is being set up, the males and females should be placed in separate aquariums. They should be conditioned for at least a week with high quality live and frozen foods. During this period, the females will become swollen with eggs.
A pair should then be placed in the breeding tank at night, and they will usually spawn the following morning. If eggs are present, the adults should be removed immediately as they will eat the eggs and any fry that hatch.
The eggs will hatch after 24-36 hours, and the glowlight tetra fry will become free swimming within two to three days. Once the eggs are hatched, it’s important to keep the aquarium in darkness, as the fry are sensitive to light.
The freshly hatched fry should be fed infusoria at first and then can be moved onto microworms and baby brine shrimp after the first few days. Commercial fry foods are also acceptable.
Glowlight Tetras are a wonderful community fish and they will do well with most similar sized, peaceful fish. These include small tetras, guppies, platies, swordtails, mollies, corydoras catfish, gouramis, and several dwarf cichlids, including Bolivian rams and kribensis cichlids.
Large and aggressive tankmates should be avoided. Many of the larger fish like angelfish may see them as prey, while aggressive fish will harass them mercilessly until the glowlight tetras become stressed and ill.