These prawns can be found in prawn fishing ponds (no pun intended) in Singapore. Families pay a different price for the number of hours they want to fish for the prawns and they get to to keep what they fished. There are options for them to bring home and DIY or to Bar-B-Que at the farm or to ask the restaurant to cook for them (at a price).
It's fresh water and hence the taste is more bland than saltwater prawns. Been there, eaten it