Once in a while, you are supposed to have bought a particular type of fish or ordered it from a restaurant, but what you get may be different in terms of taste, texture etc. Normally this is just a relatively minor nuisance … But in one of these whacky stories from Hong Kong, about 14 people complained over the last 6 months or so having consumed some ‘cod fish’ from a supermarket. Some of them even complained about excreting oil! The authorities were pretty puzzled, until they discovered that the ‘cod fish’ was not what it said to be, but rather a totally different type of fish called ‘oil fish’. This oil fish is normally not recommended for human consumption, and its main use is for extracting oil for industrial purposes. (One of my colleagues remarked that, since we all don’t have a mechanical stomach, little wonder we can’t digest the industrial-grade oil …) How the oil fish made it to the supermarket shelves was indeed a most interesting question. The supermarket did eventually of