Material that has been treated with a fire retardant could have an adverse effect on you discus. Make sure that the batting or whatever material you are getting has not been treated with these chemicals. I would just spend the extra dollar and get the material from a pet store to make sure that it is okay for the intended use. Just because several people are buying it for the same purpose does not mean that it is okay. It could be several people that will be having the same problems (and dead fish in their tanks) down the road. JMO.