Cichlid disease?

Question
My African Cichlid tank is having fish die off.  I have had ~1 fish die per week for the last month.    The tank is a 65 and is well established.  All levels are optimal, PH is 7.8-8.0, Ammonia/nitrite/nitrate OK, temp 76F.  

Currently I have noticed that 2 of the fish have a distorted shape along their jawline.  They look like they are breathing harder than the rest of the fish.  It doesn't look like they are closing the gill plates.  When they eat, they spit up their food.

For the time being, I have hospitalized the 2 sick looking fish.  I have added ~1 tbsp of salt and a copper treatment to the tank.  The fish are swimming in a normal way.

The fish that died earlier seemed to be taken very quickly.

Is this a parasite?  Thyroid?  Some disease?  

Thanks,
Jim

Answer
Hello,
It is hard for me to tell.  The only thing that comes to mind is oxygen.  Are they having enough oxygen?  Your filter should splash water down into your tank water causing movement all over the tank.  Adding an air stone would help circulate the water.  Never fill your tank to the top.  Leave a space, so that the water from your filter splashes down into your tank.  If this is not the reason, then it could be viral.  Sometimes fish die, with no apparent reason, and it remains a mystery.  Since all your water chemistry is safe, and the PH is also right, I can't think of anything else at the moment.  
Lynda