Blue Acara, Concerned something is wrong with fin

[lullasmomma]

Can anyone tell from this photo if there is something going on I can treat for? There is a single dot on the fin, looks like a bubble. A tiny air bubble. There are 3 other fish in the 55 g tank. 1 7yo Silver Angel and 2 cichlids purchased with the acara 2 weeks ago.
https://i.imgur.com/gTFAzks.jpg

 

[Autumnsky]

You may just try a salt dip and see if the dot falls off. If not gently scrape across the dot and see if it comes off.
https://www.aquariumcoop.com/blogs/aquarium/aquarium-salt-for-sick-fish