I'm a bit scared of melafix, have used it in the past and it killed otherwise healthy fish in the tank. Same happened the first time I used pimafix, but I've used it again since (during the whitespot outbreak) and it worked ok. Have put some in my big tank last night, some of the fish are looking a bit stressy, but I bet I would if someone dumped a load of chilli peppers on me too *lol* I only used it as a last resort, as since I've done water changes and the salt content's gone down, the white lips returned on two of the rainbows. So much for the salt level not doing any good!