My betta used to create his own bubbles by making a nest under the filter outflow. The flow would push the bubbles down into the water and he obviously thought they were fry escaping, because he'd catch them in his mouth and try to take them back up. :p
May I make a suggestion on your stocking? Not meaning to lecture, just a few points:
- even a bristlenose pleco is probably going to be too large for your tank as they get 6 inches long. They also have a really big bioload, so he's overstocking you.
- tetras really prefer groups of six. In smaller groups, they are far more easily stressed and therefore more susceptible to disease.
- platies prefer groups of 3.
If I were you, I would rehome the pleco and choose between the platies and the tetras, then boost the group of whichever to an appropriate number. Yes, it gives you less variety in the tank, but the fish are happier. :) Ten gallons is really too small for a varied community.
Good luck with your bubble-riders! :p