I'm so sorry about Trooper, .

I would isolate the fish showing symptoms, and definitely start treating with kana. You may also want to do a flashlight check for velvet, and consider adding RI+ or Maracide to your treatment.

If this is fish TB, then we have to consider that all of the fish in the tank have it/carry it. Some may not show signs of it, or may not do so right away. It's quite variable in course (in that some fish may succumb, sadly, soon after contracting it, while others could live a period of time with it).

~Ash