Puffer fish are able to "puff" themselves to an enormous size whenever they are frightened, disturbed, or taken out of water. Its tissue contains a poison that is produced by the fish. The poison can cause numbness around the mouth, nausea, vomiting, diarrhoea, giddiness and abdominal pains. It can interfere with nerve transmission and lead to symptoms such as difficulty breathing, muscle twitching and tremors. In Singapore, cooks preparing this dish have to be specially trained and qualified. Thus, poisoning by puffer fish is seldom encountered.