Crabs are superb in taste but beware my friend. A Thailand foreigner who's name is Jeff Haymes recently exposed of what he learned in Thai Black Market.
Haymes who claims working at NBC ,posted facebook a collage photo of poor crabs allegedly being injected with toxic substance called Formulin (contains higher toxicity level compared to formalin).
"WATCH FOR CRABS!When buying crabs in the market look for injection marks such as these when buying crabs imported from China. Chinese inject the crabs with formalin to keep them fresh but it is a highly toxic substance. I heard this today at a Thai market" Jeff Haynes posted.
A similar post also published in All Singaporean Stuff blog.
Formulin is a mixture of 67% methanol and 33% formaldehyde a pungent gas, with the chemical formula HCHO, used as an antiseptic, disinfectant, and for preservation of biological specimens.It is also used for the embalming of human remains.