[Dimmie Dunce]

No world event.
Give them an underwater home
Let them appear and go wild.

What happened in world events???
HMM?
HMMMMMMMMMMMMMM?

Everyone went to flavor faction of the month.

Let the fish be free. Give them a place water mages (Like me, because i am awesome) and sirenian fishies can live in solitude.

Edit:

Make the place small, like Illberg's start. Let them build up from it. Maybe give them like one or two apped for leaders who arent really leaders they're more like roaming big bandit PCs like Penelope.

More bandits.
More wanton CRIMINALS
MORE

FISH!