boxfishys need help!

[Scorpion]

ok... so now. the fish is doing much better. it's eating the brine that we are feeding it. but.. now i see ick on it's fins and body. we have a cleaner shrimp, but it's not going to it. is it because the ick is not bothersome to the boxfish?

also... i'm not sure if i wanna do a freshwater dip, cause the last time i did it for a damsel, the ick stayed and the fish died. i put the fish in the freshwater for 30 seconds, then back into the tank. but this was when the tank was fairly new.