Two men are being investigated by the RSPCA after they ate a live fish in a Sydney pet shop and posted the video online.

Vision of the stunt, which was filmed at Petbarn in Penrith, has been watched more than 7 million times.

In the video, one of the men can be seen pointing at a goldfish in a tank and saying "let's go that one there".

A staff member scoops the fish out of the tank and puts in a plastic bag, before leaving to get elastic bands to seal the bag shut.