Sorry I missed your query. Hope you still see this. Glowlights' eggs (like most tetras eggs) are very delicate. It would be very difficult to catch them out of a community tank and hatch them separately successfully. There are several requirements for their successful breeding, in case you would like to try.
The eggs need fairly soft water to hatch well, though they will spawn in quite hard water. That means preferably below about 70 ppm total hardness. (No harm in trying your tap water as is if you can't test it. If soap lathers easily in it, you should be OK.) Temperature around 24 to 26 degrees C (about 75 to 79 F). Too much warmer and hatch will be affected. They will spawn in a very small volume of water, as little as 10 litres (2.6 USA gal), probably even less. (I use 12 litres per pair, or 50 litres (13 gal) for a group of 4 pairs.) You can use fine-leaved live plants as a spawning medium, or if you do lots of spawning you can make artificial spawning medium out of coconut fibre (well washed and soaked in near boiling water for 10 minutes - with care) before use. (This takes out the tannins - brown color - and any other processing contaminants.) Coconut fibre is great as it can be reused many times, just by washing it in hot water before each use. It is very well accepted by many egg-scatterers - which glow-lights are - and much more convenient than live plants. (Your local plant nursery may sell it.) Fill the spawning area to about 1/3 with plant or the coconut fibre well teased out. (The glowlights will spawn amongst it.)
My preference is to put tetras (and most other fish) in subdued light to spawn. Their eggs will be fine. (Darkness not necessary for hatching.) If you put a well-conditioned pair (plump female/robust but smaller male) in the spawning tank, preferably in the late morning, spawning most often takes place the following morning, starting quite early. (Interestingly, they do a sort of 'barrel roll' during spawning. This is repeated a number of times with a few eggs released each time until all are expelled.) Spawning takes in the region of two hours overall. The breeders are exceptionally good about not eating their own eggs, but it is best to remove them before the eggs hatch which will happen during the night or the following day.
Depending on a few factors, you could expect a hatch of 50 to 200 larvae from a good, mature pair. The young should be free-swimming and ready to feed about 4 days after hatching and are large enough to take newly hatched artemia (brine shrimp) as a first food. (Infusoria is therefore not essential, but can be used.) Watch out for ammonia after you start feeding artemia! Hope I haven't left anything out. Good luck if you try them.
