fish acting strange

All but three of the fish in my tank are acting strange. They are all sitting on the bottom with their bellies on the gravel and are PERFECTLY still. They are all under the rocks. This has been going on for a couple of days now. The nitrates tested high so we did a water change. Anyone know why they are doing this or what else we can do?

water change water change water change.. they willl get active soon..

How much water and how often?

Is the temp in the tank good for the fish?

Water change every 3 days and check the parameters at least twice a day to keep them good.

Are you on public H2O or your own well. If public you need to check the H2O coming out of the tap. Also what is your city using to sterize the H2O. If your own well 90 percent won't hurt. H2O quality is the major problem with the fish. Cange H2O.