Shrimp is an important type of seafood. They are so tasty!
I love shrimp just had some last night actually I love them cooked all ways but made a shrimp scampi.
In the united kingdom they are more commonly called prawns.
We actually have prawns here they are more on the sweeter side to me but they are much bigger in size.
Are they freshwarer prawns? I've read they're some prawn aquaculture farm in the US.
Now that part I'm not sure now that you stated that they be in the local fish market so I would hope they are fresh water prawns and not that injected farm raised food. 
The global total for freshwater prawns raised in farms is around 280,00 tons!
So the chances of it actually being fresh water is low, they actually start off as being from the fresh water and they capture them and bring them back to those farms.
by India and Thailand with some 35,000 tons each. Additionally, China produced about 370,000 tons of Chinese river crab ("Eriocheir sinensis").
Species.
All farmed freshwater prawns today belong to the genus "Macrobrachium". Until 2000, the only species farmed was the giant river prawn ("Macrobrachium rosenbergii", also known as the Malaysian prawn). Since then, China has begun farming the Oriental river prawn ("M. nipponense") in large quantities, and India farms a small amount of monsoon
Shrimp and prawn as food
Shrimp and prawn are important types of seafood that are consumed worldwide. Although shrimp and prawns belong to different suborders of Decapoda, they are very similar in appearance and the terms are often used interchangeably in commercial farming and wild fisheries. A distinction is drawn in recent aquaculture literature, which increasingly uses the term "prawn" only for the freshwater forms of palaemonids and "shrimp" for the marine penaeids.
In the United Kingdom, the word "prawn" is more common on menus than