Prahok is a fermented fish paste popular in Cambodia. It is not a cheese, but prahok has been nicknamed “Cambodian cheese” since at least 1998, when it was mentioned in The Elephant Walk Cookbook on Cambodian cuisine.
 
   
Wikipedia: Prahok
Prahok (ប្រហុក) is a crushed, salted and fermented fish paste (usually of mud fish) that is used in Cambodian cuisine as a seasoning or a condiment. It originated as a way of preserving fish during the longer months when fresh fish was not available in abundant supply. Because of its saltiness and strong flavor, it was used as an addition to many meals in Cambodian cuisine, such as soups. Prahok has a strong and distinct smell, earning the nickname Cambodian Cheese. Prahok is usually eaten with rice in the countryside or poorer regions.
   
Google Books
The Elephant Walk Cookbook:
Cambodian Cuisine from the Nationally Acclaimed Restaurant
By Longteine De Monteiro and Katherine Neustadt
Boston, MA: Houghton Mifflin
1998
Pg. 301:
PRAHOK, a gray, pasty preserved fish, is probably the most distinctive flavor in all of Cambodian cooking and certainly the most unusual for Westerners. Its smell has earned it the nickname “Cambodian cheese” in The Elephant Walk kitchen, and its odor is reminiscent of Limburger or ripe Camembert.
 
Google Books
Daughter of the Killing Fields:
Asrei’s Story
By Theary C. Seng
London: Fusion Press
2005
Pg. 158:
(Note on “prahok”—ed.)
A very potent and odorous mixture of minced fish, definitely an acquired taste. Known as Cambodian ‘cheese’, the potency and feeling remind me of eating French Roquefort cheese. It is one of my favorite Khmer dishes.
 
Phenomenon: Food in Cambodia
Phil says:
9 FEBRUARY 2006 AT 9:27 AM
Haven’t seen prahok as “rotting fish”. Normally it gets translated as either “fish cheese” or “Cambodian cheese” which I think is spot on.
 
Google Books
Cravat-a-licious:
The Selected Works of a Master Chef Critic
By Matt Preston
North Sydney, NSW: Random House Australia
2009
Pg. 100:
One thing you won’t find on the menu at Bopha Devi is Cambodia’s own rather unusual fermented fish paste called prahok. ‘It is delicious,’ Chan assures me, ‘but often described as Cambodian cheese, and you can imagine what cheese smells like to Asians!
 
Google Books
National Geographic Traveler: Cambodia
Edited by Trevor Ranges and Kris LeBoutillier
Washington, DC: National Geographic
2010
Pg. 59:
Prahok: Commonly made from mudfish, this crushed, salted, and fermented fish paste is used as a seasoning or condiment. Thanks to its distinctive smell, prahok is known as “Cambodian cheese.”