Not for owning the fish, but for not having them staffed 24/7. When I read the law, I didn't see anywhere it talked about it only applying to pet stores. It seemed to me it would apply to everyone.
And perhaps I'm mistaken about this, but I thought a criminal was a person who broke a law. And if this law had been passed as originally written, then anyone who owns 50 fish in a tank and does not have staff caring for those 50 fish 24/7 would be breaking the law, and thus a criminal. The law doesn't have to say "you will be a criminal if you don't do this." It just has to say "you must do this," and then if you don't, you become a criminal.