Marine velvet is awful I lost 26 out of 34 fish to it last summer. I wouldn't of lost as many if I had acted quicker and sucked it up and set up the qt tank and did the copper treatment earlier. It was a
HUGE PITA to catch that many fish out of two three feet tall 230g tanks, then QT them all and treat them in a 120g with copper for 2 weeks (doing 50% water changes every other day, so ammonia wouldn't spike) then let the displays sit empty for another 6 weeks
but If I hadn't did it I would not of saved the eight fish that did make it, one of them being my prized king angel. My only regret is being to lazy not to have done it sooner and have had the possibility to save more of them.
Sorry to be blunt, but as I see it, you either try to treat your fish with copper or watch them all die. Keep in mind your rock and corals will be useless if you treat the display and the fish need the copper treatment for 2 weeks and be out of the display for another 6 weeks (if you didn't treat in the display) before the velvet is gone from the system. If it's not worth it to QT and save what fish you have left & if it's not to late for them already (MV kills fast) then know that you will need to wait 8 weeks after the last fish has died before adding any new fish to the display, this needs to be done in order to not infect the new fish with MV.
FYI even when you start copper treatment fish will still die during the 1st week. It wasn't until the 2 week of treatment before fish stopped dying on me.
Here's a link to my thread when my fish had marine velvet. Lots of good info in it and some graphic pic.'s
http://www.canreef.com/vbulletin/sho...=marine+velvet