Hi,
To better assess the issue we would need to know what type of tropical fish they are (example - mollies, betta etc), how many of each fish you have, and how big your tank is. From what you have said, I'd say it is not an ph level issue but exactly what described - 'like they have no air'. Your fish sound like they don't have enough air flowing through their water. To temporarily solve this (and this should only be for a few hours maximum until you can buy an air pump) you will need to move the filter in the tank (provided it is an internal hanging filter) so that the outflow of water skims across the surface of the water in your tank to provide a rippled water motion. You will however need to buy a air pump ASAP, and a air stone and a clear tubing (provided at all pet stores) and connect the tubing to the pump and the other end to the air stone and put the air stone in your tank. The pump should be placed higher then the top of the tank if possible in case of a power outage, otherwise the back flow of water will end up on your floor. The air pump will provide your tank with oxygen so your fish can breathe.