What Do Glowlight Tetra Eat in the Wild?

In the wild, glowlight tetras (Hemigrammus erythrozonus) are classic little opportunistic feeders. They come from slow, tea-colored streams and tributaries in South America where the water is full of leaf litter and tiny drifting life. Most of what they eat is small enough to fit in a pinhead: insect larvae, tiny worms, micro-crustaceans (think copepods and water fleas), and other zooplankton they can snap up from the water column. They will also pick at biofilm (that slimy layer of microorganisms on plants and wood) and grab bits of organic detritus as they go, especially when live prey is scarce. A big part of their menu is whatever the current delivers. In shaded forest streams, ants and other small insects routinely fall into the water, and glowlights will hang in midwater and dart up to grab them. When conditions are right, they will also take fish eggs or newly hatched larvae if they can find them - not because they are "predators" in the big-fish sense, but because protein is protein and they are built to peck at tiny moving targets. What this means for your aquarium feeding is pretty straightforward: they do best with small foods offered often. Aim for 1-2 small feedings a day, only what they can finish in about 30-60 seconds. A quality micro pellet or fine flake works as the staple, but you will see better color and more natural behavior if you rotate in small frozen/live foods a few times a week - baby brine shrimp, daphnia, cyclops, and bloodworms (chopped if they are large). If you have a community tank, make sure food actually reaches them; glowlights are polite eaters and can get outcompeted by faster fish. If you want to mimic their natural grazing a bit, a mature tank helps. A piece of driftwood, leaf litter (like Indian almond leaves), and healthy plants encourage microfauna and biofilm they can pick at between meals. You do not have to rely on that for nutrition, but it lines up nicely with what they are doing all day in the wild: constantly sampling tiny foods and whatever the stream brings by.