The Firefish and Gramma should be OK, I think... The colours aren't too similar, and they aren't likely to enter a war over territory, since firefish are open water swimmers and Gramma's are rock dwellers...
new addition, pics and stories later, just acclimatized and put them in the tank, and one has some white speckles , so ive netted them and bagged the, and im doing a raw freshwater dip, no PH change, just the temp adjust. im going to leave them in their for a minute
If you have whitespot and corals, you will have three options open;
1) Set-up a QT tank and either copper or hyposalinity treat all fish in the tank
2) set-up a bucket with fresh salt mix in, a heater and air-line before transfering the fish into it. Change the fish to a different bucket with fresh salt RO in after 24 hours and sterilise the equipment in to old bucket. Repete for the rest of the week.
3) Do nothing and hope.
IME with marine Whitespot, fresh water dips do nothing to remove the parasites themselves and simply stresses the fish more, making them less able to fight off the infection.