High Quality Content by WIKIPEDIA articles! Cyanide fishing is an illegal form of fishing common in South East Asia, which usually uses the chemical compound sodium cyanide. Since 2000, increasing restrictions on illegal dynamite fishing have led to an increasing growth in this indiscriminate method particularly as it can be used without generating noise. The use of cyanide as a fishing technique was first documented in the Philippines in 1962. An estimated 150,000 kg of cyanide is used in the Philippines annually by the aquarium trade and more than a million kg have been used since the 1960 s. In seawater sodium cyanide breaks down into sodium and cyanide ions. In humans, the latter blocks the oxygen-transporting protein haemoglobin, the haemoglobin in fish is closely related to that of humans, and can combine with oxygen even faster.