oxygen in water

Question
My saltwater fish (Mostly minnows) seem to be gasping or gulping alot of water past their gills. They aeem to be hovering at th top of the tank also. I have an air stone in the tank. Can they be o2 deprived? how do I check the stone to be sure air is desolving into the water?

Answer

John,

yes they are  o2 deprived.  Remember seawater contains only 7ppm of o2. They only way that I know is to buy a dissolved o2 test kit this will tell you right away. they are very cheap.  Also I do not use air stones anymore.  I use powerheads, they circulate o2 throughout the  tank. If your ph is too high that effects o2 too.  

Bottom line increase your circulation and your o2 problems will be solved.
I hope this helps
Todd