Bubble on Jacks Dempseys tail

[Jade]

He's had this bubble on his tail for a long time at first it was smaller it only took up one of those white spots, i dont remember when it got bigger i just noticed it one day, it takes up about 4 spots now and hasnt grown since. any idea what it is, do you think its anything to wrry about?

[logjil]

did the jacks fins ever get damaged, split-after healing i saw this before.

[Jade]

i dont know if it was injured but thats what i always figured had happened
like maybe another fish bit him and it just healed that way