Prawns can also be of the fresh-water type.
If you have ever visited a prawn farm you'll see the vast acres of artificial prawn ponds. And realize that the water must be fresh, because some farms are hours from the nearest beach. It's hard to imagine the woman who runs the prawn farm retail store is a prawn "farmer"! :) I failed to resist asking what the prawn feed looks like--yeeew--the same smell as rabbit feeds!
It's a pretty boring sight, a few ponds would be empty and you see the muddy bottoms. There's huge 5 incher PVC pipes leading from pond to pond with a valve sticking out of the trail and the occational old golf cart with wet baskets.
Both saltwater and freshwater prawns are delicious. :d :D If you are lucky enough to run across one, BRAKE THE CAR! STOP! DRAG the others into the farm, say hi to the prawn farmer and grab a few pounds for dinner, they taste oh so good when they are fresh!
Warning: stopping at a strawberry garden or a carefully hidden ice cream factory is a much more devastatingly fun and even more communal experience. Don't not attempt to resist, you will gain weight and happily obey all law in strawberry and ice cream land (er.. farm/factory).
This info comes from someone who used to live next to a prawn and fish farm and volunteers to feed them whenever possible! (living next to a prawn farm sorts sucks, there's this horrible smell when they drain the water out of a particular pond--I don't think it's the left over prawns, but that bottom with all that the prawns excrete and swim in is kinda gross and definitely smelly in a fishy way. But realizing how bad cow manure piles smell when you go on a country side driving trip makes drained prawn pond smell minor in comparison).
Just think on the bright side--prawns taste good!