Number 4 right here.
If fish keeping was made illegal worldwide and was support by all governments it would become impossible to keep them and I for one would give them up. Sure, now people can get away with keeping illegals but it is only select fish. If it was every fish it would be easy to decide whos houses to check first, 24,982 people here would make it to the list. Others that keep masses of tanks would make it to the short list, easy done and all the info is on this site. What you own, how many tank, size of the tank and most importantly your location (which, don't kid yourselves, would be handed out). Being on sites like this would be like flying a flag out your window.