Most of your tetras are distinguished by the shape of their bodies where the females are more plump than the streamlined males...... If they are seen chasing each other (vigourously) around the tank, they are in fact spawning and after such session, the females will also appear much slimmer.
The eggs are minute (and mostly transparent) and very difficult to see if you do not know what you're looking for and are (in any case) eaten by the parents if the parents are not removed immediately after the spawning process....... If you are desperate to see if there are eggs,.... the water may be stirred above any thickets or plants in the tank, and then looking from the bottom upward (towards the light, you may see some eggsswirling in the stream made by your hand.
