Welsh
Aquarium Advice Freak
All I can describe it as is that the tetras are stabbing the water with their noses, they can swim normal but seem to be facing downards at an angle and pecking the water. Is there something wrong?
Hmm.
So from what you're saying, my Tetras act pretty much the same except for the pecking the water...
Unless they have a noticeable issue (like bloat, gasping, damaged scale, No appetite).. if it was me, I'd just let them be.
Your Params are excellent, so I'd just keep an eye on them but not stress over it.
BTW, do you have any other fish in that tank?