I would be willing to bet that the frags would have been OK if left alone, you friend should have left it in his tank like you asked him to. Even if it died and went away it would not have bothered his tank in any way. When you frag it it takes a couple of days for it to be happy again and will shrivel up to a small little bunch which is most likely what happened to to your friend. Xenia is a weed and grows extremely fast, the best way to keep it isolated in you tank is to place it on a rock in the center of you sand bed since it will not cross the sand it will stay there. Other wise if left unchecked it will spread till it pretty much takes over your tank. Fraging it isn't hard either, all you have to do is cut it off at the bottom with a pair of scissors. The more stalk you leave the better it will do after cut, although I once cut just to tops off of about 10 stalks to see what it would do and 6 out of the 10 survived. Keep in mind if you leave a piece it will come back. As far as the nastiness that comes out of it when fragged, if your fragging just a couple of pieces you should be OK. But if your going to do allot of fragging like I used to you should always run some carbon to absorb what come out of the Xenia. After fragging the best way to get it to attach is to put some rock rubble or CC in the bottom of a plastic container, I use the ones that you get the potato salad from the grocery store. I put the frags in and cover the top with some Bridal Veil which you can get from the local craft store. Put it in your tank, I wedge it between some rock. Leave it in there for several days and it will attach itself to the rock. Once attached you can take it out and glue the rock where you want to.