I'm not sure what species a "red glass barb" is, but it may be a colour variant of the Rosy Barb which is Pethia conchonius. This species along with some other was formerly in the Puntius genus [see profile for more, click shaded name].
Be grateful your fish are spawning. That means they are obviously healthy and happy with their environment. If we provide what a fish species requires to be healthy, most will then spawn, and all of us consider this an achievement. Aside from separating the fish, anything you do to stop spawning such as temperature changes or inappropriate environmental or water conditions, etc, would obviously involve harming the fish, and I'm sure you don't want to do this.
Most of us have fish in community tanks that spawn but other fish are quick to eat eggs or fry should the eggs survive to hatch. Obviously if fry are surviving to the extent you describe there must be plenty of cover for them, and sufficient minuscule food. Natural predation by other fish in the tank is the best way to limit fry. And by this, I simply mean having sufficient fish in the community so that the survival rate of fry will be much less.