Freshwater water change, 70 gallon tank

Question
I have a 70 gallon fresh water tank with approximately 12 fish (or 35 inches of fish), some of these fish I have had for years (Tinfoil Barb, Silver Dollar, Parrot, Pleco, Rainbows). This tank has been set up for many years too. I did a 40% water change yesterday and it seems that still today all my fish are trying to get air at the top of the tank. I have two air pumps, a 400 Fluval filter, and to stone air rocks, have added slime coat and water treatments too, what should I do?

Answer
You may want to leave it alone for a little and let everything settle, try feeding them. Other than that there isn't much more you can do. Also test the water and see if there are any levels off. Most stores will do it for free, or you can obtain test kits from those stores, I recommend the quick dip strips.