Toss in a pair of bootstraps to give them the opportunity to pull themselves up and out of the tank by them. Hang them just out of reach.

Make them dip in fish guts first. Start them in the middle of the tank. If they make it out, they get to pick the next billionaire.

Also throw in any politician who’s ever taken a bribe campaign contribution from billionaires/corporations

There is a competitive aspect: a quiz show where contestants compete to win the right to push the billionaire into the tank.

I’d watch