White spot

several different ways :D

Seriously though, are you certain it is ick? If so is it only a lion fish in your tank or is it all the inhabitants? I'm guessing you don't have any invertabrates in your tank with the Lionfish?

If that is the case I would drop the salinity in the tank, down to about 1.016, and keep it there for several weeks. I've never had ick but many people recommend this method.

Ideally taking everything out of the main display tank and putting them in a quarentine tank is better. Allowing the main tank to be empty for 6 weeks. Ick will survive in a tank, dormant for a month or better. That is the only sure fire way to take care of it without using a medication in your main tank.

If you don't ever plan on having inverts or corals you can medicate your main tank, using copper or formalin or other Ick medication, but it will be difficult to completely remove the medication and can cause problems in the future if you do ever get sensitive animals.
 
Yes, that would kill them. Removing the lion for treatment in another tank would be the better option, as copper based treatments will also kill the inverts.
 
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