Beth,
2day i got a product called "rapid white spot remedy" by aqua master (for freshwater tanks), it is 37mg/ml of formaldehyde and 0.32mg/ml of malachite green. i hope this is wat i was ment to get, got it from work and my boss said it was the same stuff.
i did a 35 min bath this evening during which the tangs breathing increased but was not rapid, after he was relased back in to QT he was fine and active, feeding straight away (he is a pig in the first place). he is still covered in black ich though...how many treatments will it take to see an effect on the black ich.
thanks for ya time Beth :happyfish