Has your oranda been treated with praziquantel before? Your goldfish is exhibiting typical fluke symptoms. Flukes are dangerous parasites categorized as trematodes that attack the skin and gills of your fish. Their presence can be associated by clamed fins, bottomsitting, flicking and labored breathings. Treat ALL your fish in contact with the oranda with prazi. Should be available as Droncit or Prazipro and dose at 2.5 mg per liter. Ignore the instructions prescribed on Prazipro bottles. It takes 3 days before prazi wears off so redosing is necessary.
Day 1 -- remove carbon, perform water change with vacuuming, and add Prazi to tank
Day 2 -- add Prazi
Day 3 -- do nothing
Day 4 -- do nothing
Day 5 -- do nothing
Day 6 -- add Prazi
Day 7 -- add Prazi
Day 8 -- normal partial water change with vacuuming
Day 14 - normal partial water change, then add prazi
Day 21 - normal partial water change, then add prazi
Day 28 - normal partial water change, then add prazi
Day 35 - normal partial water change, add carbon, treatment is complete
Remove carbon by the way.