What are your water parameters, stock, and tank size? Have you recently accuired new goldfish and did not quarantine? many questions. first of all is water parameters. tell us whats up. Do a good 50% water change and add your usual water conditioners.
i got a video of them swimming fine
i noticed one of the goldfish almost blood like scales, then i did a 50% water change, cleaned the filter, and added a air stone and it went away?