Do I need to treat my tank?

[FishFry]

Hi there, new to the hobby and my tank has been up and running for about 3-4 months now. Current residence include one male threadfin rainbow, two kuhli loaches, four chili rasboras, handful of neocaridina shrimp, and 5 nerite snails.

My concern is with my threadfin, about two weeks ago he developed 3 or 4 white spots which I was concerned were ich then 2 days later both loaches and one rasbora got one spot each so I ordered ich x. Now everyone is acting 100% fine with no spots, no death, all eating. The only one that has lingering issues is the threadfin who now has what I would refer to as a dull saddle area on his body. Is this scars from ich, a different disease, nothing and I was just paranoid?? Should I still treat since I did see white spots? 
Unfortunately, I have no pictures of the white spots but i’m including pictures of the threadfin. 

Edited March 21 by FishFry

[Tony s]

I might. saddle back and white spots can be signs of columnaris. if you have a quarantine tank you could just pull him and treat the q. tank. or you could treat the main tank. kanaplex or maracyn2 would be best. follow directions very closely. available from most local fish stores. I'd add some catapa or indian almond leaves as well. I'd say add some aquarium salt too, but you have snails.

[Colu]

Looks like  columnaris that's a gram negative bacterial infections that spreads more quickly at temperatures over 75°F and can kill in 24hr to 7 days depending on the stain the most effective treatment I have found is a combination of kanaplex and jungal fungus clear fizz tabs containing nitrofurazone following this treatment plan i would quarantine and any fish showing symptoms and treat straight away kanaplex and nitrofurazone medication be harmful to shrimp and snails  if your treating the main tank I would remove them @FishFry