The bubbles at the front could be either from the filter or the start of a bubble nest. Difficult to say. Good luck on finding a bubble nest, though. Just remember that some boys blow smaller nests and some blow bigger nests.I am putting more plants in right now, and there are 6 tetras. I can't see but 2 in the picture though. They hide behind the plants.
Does anyone notice the bubbles at the top? Those aren't his are they. I never see him make a nest, yet bubbles gather at the front and around the filter input tube. I guess they're just the bubbles that the filter causes.