Firstly, thanks to everyone for responding. I am new here, but I have already gained some great insight from this site.
to update on the quarantine/ich treatment...
I am not sure how to proceed - I treated with malachite green/formalin for 3 days. I began treatment because there was one spot on a STs tail. There is no longer any sign of ich (no white spots), and all I am going on is the fact that the swordtails are bashing into stuff. They are still doing this after the 3 day treatment. Today did a water change of ~40%. The SAEs are getting algae wafers to supplement diet. I really want to put them in my main tank, but I am afraid of putting disease in there! How long should I wait? What would you guys do? I am just confused because there is no actual sign of disease other than the occasional bashing by the STs.