Saltwater Ick

[Tbare89]

What is the best way to treat it while a fish is still in the tank?

 

[snorvich]

Please read this.

 

[sandwi54]

If you ABSOLUTELY do not want to or cannot get the fish into a QT, then hyposalinity is the only choice. However, the success rate is much higher and it's easier in a QT.

 

[MrTuskfish]

What is the best way to treat it while a fish is still in the tank?

I don't think there is a good way. There are "maybe" ways, but not a good way.