RSPCA investigators are trying to trace people who may have mistreated goldfish in Chorley.
The charity says the incident happened at a bonfire event at the Malt Shovel pub on November 2.
Inspector Kate Levesley said: “Sadly we have had some reports of people taking the goldfish – which were being offered as prizes – and removing them from the water as well as throwing them around.
“We would really like some more information.”
Anyone with information can call 0300 123 8018.