Bitis gaboned , most commonly known as the Gaboon viper , is a viper species found in the rainforests and savannas of sub @-@ Saharan Africa . Like all vipers , it is venomous . It is not only the largest member of the genus Bitis , but also the world 's heaviest viperid , and it have the longest fangs – up to 2 inches in length ( 5 cm ) , and it have highest venom yield of any snake . Two subspecies are currently recognized , including the nominate subspecies described here .