I didn’t think this was a thing any more (the last time I saw goldfish offered as a prize was in the 1980s when I was a kid!)
However, there was a stall doing exactly this at a large firework display/concert on Saturday at a country house in East Suffolk (people from the area can have a good guess at where I mean)… Loads of goldfish in tiny plastic bags ready to be won if you could throw some darts accurately. I then saw a woman later that evening casually swinging her arm back and forth as she walked with a goldfish bag in hand, bashing the poor fish around in its tiny bag.
AIBU to think this practice is cruel and irresponsible, and that the country house who allowed this should be ashamed.