It is the result of irresponsible hobbyist. People get them, lose interest or run out of space and then release tem into the wild. In the case of this species it has be environmentally and economically very damaging in many areas. People need to take responsibility for their fish and things like this would not happen. I agree it's sad (I'd like to have one), but the government steps in when people do the wrong thing. I understand why they were banned. BTW, they have been banned for a while now.
was it in fact a hobbiest that releasted one? or an emigrant that didnt truley realise what damage he was causing. how many invasives has the government released that have damaged an eco system?