In a fish tank, fish will
eat nearly anything. So if you have
30 fish, the fish will start eating any fish that looks sick or different. This will continue until you end up with
one very large fish, usually the goldfish. Much like when a message board gets
run over with a few friends who want to monopolize it. They will ceaselessly troll until anyone they aren't friends with leave. Then they'll move on to another site and do the same until it too ends up with
one or two users.