| Temperature | 24–28 °C (75–82 °F) |
|---|---|
| pH | 6.0–7.0 |
| Min tank | 10 gal (38 L) |
| Adult size | 4 cm |
| Lifespan | 5–7 years |
Most people buy a Glowlight tetra on looks alone, then wonder why it sulks. The fish is fine; the setup around it usually is not. The Hemigrammus erythrozonus Glowlight tetra is a long-time favourite for a reason, but it has specific needs that generic "community fish" advice misses.
At a glance
| Minimum tank | 10 gallons (38 L) |
|---|---|
| Temperature | 24 to 28 °C |
| pH range | 6.0 to 7.0 |
| Adult size | 4 to 4 cm |
| Lifespan | 5 to 7 years |
| Group size | a group of 6+ |
Where it comes from
In the wild the Glowlight tetra lives in slow, vegetated waters where cover is everywhere and currents stay gentle. Recreating that means planting densely, keeping the filter flow soft, and avoiding bright, open tanks that leave the fish exposed. Stable water matters more than perfect parameters.
Tank setup
Start with at least 10 gallons and a mature, cycled filter — see a solid swim bladder disease: fish floating or sinking before you buy. A sand or fine gravel substrate, a few driftwood branches and a carpet or mid-ground plant mass give the fish somewhere to retreat. Keep nitrates under 20 ppm with a weekly 24% water change.
Feeding
Feed a varied diet: a quality flake or micro-pellet as the base, topped up with frozen or live foods two or three times a week. Offer only what the fish clears in about 1 minutes, once or twice daily. Overfeeding is the single most common cause of water-quality swings.
A mistake everyone makes
Adding a Glowlight tetra to a brand-new tank is the classic error. An uncycled tank spikes ammonia to 1.1 ppm within days and the fish pays for it. Cycle first, stock lightly, and let the group size build up gradually.
Good tank mates
Peaceful, similar-sized neighbours work best. Avoid fin-nippers and anything large enough to swallow the Glowlight tetra. A planted community with a solid kuhli loach breeding in the mix tends to settle quickly.
If you are new to this species
Start with the minimum 10 gallon tank fully cycled, hold the temperature at 24 to 28 °C, and feed a small amount once or twice a day. Resist adding tank mates in the first two weeks so the Glowlight tetra settles without competition.
