I'm happy to hear that your other fish are doing well so far. I asked my husband to take a peek at these photos, I wanted to see if he could confirm my suspicions... and after a lot of staring at your photos, both of us agree that it looks a lot like fish lice, and very possibly your tank is infected. That means even though they may not be showing any signs at present, your other fish are likely to come down with the same problem, and will need treatment to be rid of the problem.
Of course, we can't be 100% sure via internet with blurry photos, but I would say there is a 75% or better chance this was fish lice, so keep a very close and careful watch on the other fish. If you don't yet have quarantine set up, now would be a good time to do it. Its always much safer to medicate in a quarantine tank, and when dealing with parasites, if the fish are out of the system for the right length of time, the parasites die due to lack of a living host to feed from, which saves having to medicate a show tank, main tank with inverts, etc.
Because my visits here are still a bit sporadic, I want to leave you with enough info to help you if you should notice a problem with the other fish. If you can't medicate in a quarantine this medication should be safe for the main tank, but please follow the instruction to the letter and don't overdose. The medication is called Praziquantel. This is not a cheap medication, I must warn you... but the only other I know is safe for those fish but not main tank would be Dimilin, and lately most people seem to be having a hard time in finding it.
The Praziquantel can be found at Fosters & Smith, its called PraziPro Parasites in Pond, Disease in Pond: PraziPro Praziquantel Treatment
I don't know if somewhere else would have it cheaper, you'd have to search. Keep me posted, I hope you don't end up needing to deal with that... but at least now you are forearmed if you do. Best of luck to you and happy fish keeping!