My understanding is that they very rarely morph by themselves as Mexico and New Zealand are both very low in iodine. They can be forced to morph with the addition of iodine, feeding thyroxin (as in sweetbreads---sheeps thyroid gland) or lowering the water level, or all three. Doing this is against the way they have evolved and their life is considerably shortened. Many years ago people were morphing them to try and breed them without realising that axies breed. Can't see the point myself. There are a number of ways things can be banned---Maf, Niwa or the Regional Council. Who knows why the same species can be banned or not banned, but I know the powers that be would have liked to see them banned for years but there are probably too many around.