Tetras are egg scatterers and most all breed in groups. There is no pairing. Unless you're trying to isolate a specific trait in your population (finnage, coloration, etc), don't worry about isolating them to breed.
Honestly, they're probably breeding right now! If they are adults, the group will spawn whenever the females have ripe eggs. A group such as yours probably breeds weekly. If it were me, I would put some of the plant matter you see the fish spending most of their time in into the sump (with some further blockage of the intake as the fry are not strong swimmers. or use a fry tank). Put a light over it and watch. Look for eggs on the plants since they are adhesive. If you don't see them but find fry one day, try to look for eggs the next time, that way you can learn backwards as to what to look for in the plant growth. This is how I learned how to find rainbowfish eggs.
The fry are going to be tiny. You may not even see them. Personally, it may behoove you to pull them completely into another tank, that way you can feed infusoria or green water without messing up the dynamics of the main tank- not that it would be horrible, just may not be worth it. My brother accidently bred glo-lites by just maintaining a small population of fish with lots of plants. A club member in CAFE also bred Galaxy Rasboras in a similar fashion. He pulls plants and water out of the tank, sits on it for a few days and sees fry. Pretty cool.
HTHs.
Honestly, they're probably breeding right now! If they are adults, the group will spawn whenever the females have ripe eggs. A group such as yours probably breeds weekly. If it were me, I would put some of the plant matter you see the fish spending most of their time in into the sump (with some further blockage of the intake as the fry are not strong swimmers. or use a fry tank). Put a light over it and watch. Look for eggs on the plants since they are adhesive. If you don't see them but find fry one day, try to look for eggs the next time, that way you can learn backwards as to what to look for in the plant growth. This is how I learned how to find rainbowfish eggs.
The fry are going to be tiny. You may not even see them. Personally, it may behoove you to pull them completely into another tank, that way you can feed infusoria or green water without messing up the dynamics of the main tank- not that it would be horrible, just may not be worth it. My brother accidently bred glo-lites by just maintaining a small population of fish with lots of plants. A club member in CAFE also bred Galaxy Rasboras in a similar fashion. He pulls plants and water out of the tank, sits on it for a few days and sees fry. Pretty cool.
HTHs.
