Question
this morning, all the fish are at the top of the pond looking like they're gasping for air....even the orfe, who usually stay down below, once grabbed their food.....they usually feed as soon as food is put on, but this morning they've ignored it,and I've taken it off again. Are they dying? We've had them for year's now, and some are quite  big.

Answer
I'm sorry about the fish.  When fish gasp at the surface, it's often due to low oxygen or their ability to get oxygen.  Reasons the oxygen may be low include high temperatures, low aeration, recent heavy rains, too many animals in there, recent extensive spawnings of any animal.  Reasons the fish might not be able to get enough oxygen include high chlorine, high ammonia, low pH, gill flukes, and more.

I suggest testing the pond's pH, hardness, alkalinity, ammonia, nitrite, chlorine, and oxygen if possible to rule out those problems.

How big is the pond?
How big are the fish and how many?
Have you tested any of the water parameters I mentioned?  If so, what were the results.
What kind of filtration and aeration do you have?
What is the pond temperature?
Has it rained a lot lately or conversely, is there a drought?
Do they have other symptoms?

I suggest doing the following.
Add an extra air stone even if you think you have enough oxygen in there.
Be sure the filters are flowing well.
Do a partial water change (up to 50% but not more; how much depends on your water availability) and add dechlorinator and pond salt (0.05%).
Test the pond for pH, ammonia, nitrite, hardness, alkalinity, and oxygen.  They sell cheap test kits for all of those.
Add a mesh bag of fresh activated carbon to the filter just in case something toxic got into the water.

I hope the problem is just transient.

Good luck!