Did you use any of the solutions that the fish shops use to utrelise the water they make it more fish safe. They are very good. This happened to one of my fish once it seemed to go into shock and some times you have to be careful with a sudden change of water as the temp drop can stress the fish out. You may find that in a day or so that your fish may start coming round a bit. As the tank settles and the bacteria starts to get back to normal. Good luck