Is there a way to differentiate sea prawns from farmed ones based on appearance? Can we differentiate it based on Color of prawn, structure etc?
"Farm Raised" vs "Wild Caught"? There's a difference, just not a visual one. Because wild caught seafood is dependant on their ecosystem, they are ultimately going to have an, ever so slightly, different flavor than the exact same species that is farm raised in a controlled environment. But, I'm not sure anyone short of a connoisseur would be able to tell. Either way, it's going to taste good. (But read the articles I linked to, below.) Push comes to shove, most of us buy what we can get, even if we have to "settle". Geographic location can make a difference, then again... it might not matter.
If you are in a landlocked state, local grocers probably offer farm-raised fresh-frozen. But even coastal communities don't always get fresh-caught seafood. My favorite grocer sells shrimp from Thailand. And I live (literally) 6 miles from the ocean, in a coastal NC (USA) town where local families have been shrimp fishing for generations. Go figure. I don't buy the stuff from the grocer. (Oddly enough, tourists assume it's local shrimp.)
So, how can you be sure you are getting fresh wild caught shrimp?
- You can consider having it shipped to you. Shop local fisheries online. Most suppliers will pack it in dry ice to maintain freshness enroute, or
- You could plan a vacation along the coast. Many of those fishing families have local restaurants, so enjoy as much seafood as possible. Then pack some up to take home. yum!