Flesh of the catfish belonging to the genus pangasius
. A marketing gimmick of a name used to refer to the white, skinless, boneless, fillets of fish taken from pangasius catfish. Cream refers to the color of the flesh and the "dory" part makes you think it is a relative of the dory saltwater fish, which of course it's not.
In truth it's a plentiful, hence extremely cheap, freshwater fish from vietnam and other southeast asian countries. It's bone structure allows large, pin-bone free, fillets to be removed from it and makes it an ideal food service fish.
The flavour can range from neutral to muddy. Cooking cream dory requires one to do ones best to hide this muddiness while throwing as much flavour as you can to make the fish good to eat.
The travesty is when cream dory is used for such classics such as fish and chips and the restaurants charge a premium price (similar to what they could charge for cod) for this cheap fish.