i never been there but i heard from my auntie that you can get free food at the casino. i think it's at shangri la hotel.
my auntie told me they just need to exchange the chips and pretend to sit at some jackport counter and ask for food. they served it to you free. and when you are done just change the chips back and leave. that settle your meal for the day.
Mekong river is one of the largest river in the world, saw on documentary "River Monster" the giant cat fish, giant stingray and those toothy fish all from there.