The final act of a British play titled The Last Temptation
involved a goldfish bowl, with a live goldfish inside, being thrown across the stage, causing the fish to tumble onto the ground, where it died. Outraged animal lovers sued, prompting a two-year legal battle in which the courts deliberated on whether it was possible to be cruel to goldfish. Or rather, should goldfish enjoy the protections given to other animals such as cats and dogs?
The first court ruled that goldfish enjoyed no such protections, but in 1980 the High Court overturned this decision, ruling that it is, indeed, possible to be cruel to goldfish, and that the law should not allow such behavior.
I'm not sure if there's any equivalent American law pertaining to goldfish. But I imagine that if there was then surely boiling lobsters alive would also be illegal.
The Guardian - Nov 3, 1978
Victoria Times Colonist - July 30, 1980