How awful for you, is your tank large enough for these new-comers? Although for you in this instance, that's not going to help you.
When you say they go white, are they losing their colour? Or are they covered in a film or fluff that is making it harder to see the colour? When you put them into your tank after floating them, did you remove them from the bag and place them in or pour the bag in with the fish and foreign water?
If you want to post a picture, when you respond, click on the go advanced button and not post quick reply, you then get a slightly different reply field. You can click on the paperclip and then follow the onscreen instructions to upload a photo from your computer. It would be really handy to see what the fish look like.