Its hard to say. I mean, are they up there gasping constantly and staying at the top? Or just going up for air very often? Ive seen some gouramis going up for air like every 2 minutes. Gouramis can survive in scummy water, with low oxygen just like Bettas because of their labyrinth organ. Just because this is possible doesnt mean they should live that way though.
But what I am trying to say is, gouramis can do fine if oxygen is low.
But what I am trying to say is, gouramis can do fine if oxygen is low.