Fish is staying at top of tank? Why? (More info below)
So, I have two pretty hardy mini gourami fish, well I used to have three but one had spinnings disease or whatever that is called, and so it died early on. But the other two have been doing fine until yesterday I noticed that my blue gourami has been staying at the top of the tank in the left corner. Its nose is to the surface of the water and it is just kind of staying there. When I walk up to the tank, it will swim down and it has been eating fine so far. I'm only nervous because usually when my fish act weird, they die. Anyway, is it because it doesn't have enough oxygen?
How would I go about putting more oxygen into the water, an easy way?
Also, none of the other fish are acting strange, only this one.