The glowlight tetra is a peaceful, semi-transparent characin named for the iridescent copper-to-red stripe that runs from snout to tail like a glowing filament. Hardy, inexpensive and undemanding, it is a long-standing favourite for community and planted tanks. A shoal moving together produces a shimmering line of light against dark backgrounds.
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Small, often brightly colored characin fishes popular as peaceful shoaling community aquarium fish. Tetras are kept in groups, appreciate soft, slightly acidic water and planted tanks, and range from tiny nano species to larger schooling fish.
From the minimum an animal needs to be kept humanely, up to the ideal setup. Bigger is almost always better — minimums are floors, not targets.
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Minimum
Shoal planted tank
15 gal / 57 L planted
Hemigrammus erythrozonus reaches 1.5 in. 15-gal planted minimum for a shoal of 6+, with soft slightly acidic water, dim lighting, and gentle filtration. Peaceful — pair with calm tankmates.
Recommended
Planted community
20 gal / 76 L long planted
20-gal long planted with a shoal of 8–10, driftwood, leaf litter, and peaceful tankmates. Glowing orange line stands out against dark substrate.
Strolgen / Public domain (Wikimedia Commons)
Photo coming soon
Ideal
Guyana biotope shoal
29 gal+ / 110 L+ biotope
Guyana stream biotope with leaf litter, driftwood, very soft acidic water, dim lighting, and a shoal of 12+. Best glow effect under dim conditions.
Life & growth stages
How this animal changes through its life — each stage often has its own care, diet and space needs.
Photo coming soon
Egg
Fish eggs are small, translucent spheres, often laid in clutches on plants, substrate, or in a nest — or carried/brooded by a parent in livebearing and mouth-brooding species. A dark eye spot and the curled embryo become visible inside as development progresses.
Photo coming soon
Fry
Newly hatched fry are tiny and semi-transparent, frequently still carrying a yolk sac that fuels them before they feed freely. They lack full fin structure and adult coloration, staying near cover until they can swim and forage on their own.
Photo coming soon
Juvenile
Juveniles look like miniature adults but with developing fins and muted or different markings; many species shift pattern and color as they mature. Growth is rapid at this stage given clean water and steady feeding.
Adult
Adults show the species' full size, finnage, and mature coloration, and are sexually mature. Many fish develop sex-specific differences in size, color, or fin shape, which can intensify during breeding.
Habitat & enclosure
Keep a shoal of at least 6 (ideally 8-10) in a tank of 60 litres (15 gal) or larger. It prefers soft, slightly acidic water but is adaptable: temperature 22-28 °C (72-82 °F), pH 5.5-7.5, soft to moderately soft (GH 2-12). Provide gentle flow and a well-planted layout with open swimming room.
Like many soft-water tetras it shows the richest colour over dark substrate in dim, tannin-tinted water, though it tolerates a broad range of typical community conditions.
Substrate
Dark fine sand or gravel best displays the glowing stripe. Driftwood, leaf litter and live plants provide cover and the soft, tannic conditions it enjoys.
Equipment & setup
A gentle sponge, HOB or canister filter plus a heater covers the essentials. Subdued lighting with some floating-plant shade suits it; CO2 is optional and only for high-tech planted aquascapes.
Diet
Omnivorous micropredator. Accepts quality flake and micro-pellets; offer frozen and live daphnia, brine shrimp, cyclops and microworm regularly to intensify the orange-red glow line and maintain condition.
Behavior & temperament
Peaceful and somewhat shy mid-water shoaler that gains confidence in larger groups. An ideal community fish alongside other small tetras, rasboras, danios, Corydoras, peaceful dwarf cichlids and small livebearers. Avoid boisterous or fin-nipping tankmates.
Health
Hardy but susceptible to ich and other stress-related diseases in poor or unstable water. Maintain stable parameters, quarantine new fish, and keep nitrates low through regular water changes.
Tips, DIY & hacks
A great beginner shoaler that pairs beautifully with neon and rummynose tetras for a multi-species school display. Tannins from catappa leaves or peat filtration deepen the red line. Breeding is achievable in soft, acidic, dimly lit water with fine spawning mops or plants and adults removed after egg-laying.
