From A Wiki of Ice and Fire
Basilisks are said to infest the jungles of Yi Ti, and were once numerous in the Basilisk Isles, lending them their name.
In some places they are used to fight other animals, such as dogs, as wagers are made on the outcomes. A basilisk is able to tear a large dog to pieces.
Basilisks are venomous and are the source of 'Basilisk venom' , a paste spiced with basilisk blood which gives meat a savory scent but which induces a violent madness in any creature with warm blood, whether man or beast. 
A Clash of Kings
When Daenerys is visiting the docks at the port of Qarth she dismounts from her silver beside a gaming pit where a basilisk is tearing a big red dog to pieces amidst a shouting ring of sailors.
References and Notes
- ↑ A Game of Thrones, Chapter 23, Daenerys.
- ↑ The World of Ice and Fire, The Basilisk Isles.
- ↑ A Clash of Kings, Chapter 1, Arya.
- ↑ A Clash of Kings, Chapter 17, Tyrion.
- ↑ A Dance with Dragons, Chapter 40, Tyrion.
- ↑ A Clash of Kings, Chapter 63, Daenerys.