I need some personal, experienced, Green Spotted Puffer help!?

I have keep fish for many years and even built a custom tank. The fish with ick will always die. Never have I ever cured one or a tank. In my salt water tanks (I have Two) the sea salt was always in the water before the fish. I think your fish might get more friendly if you try hand feeding, use a slice of cuber. Also I have found out using beach sand stops the adding salt to the water. Also try leaving the tank lights off a little longer each day that might help.