Syrax had yellow scales. She was huge and formidable, but not as fearsome or experienced in battle as Caraxes. She was kept in chains and exceedingly well fed. She had not hunted for years at the time of the civil war.
Syrax laid at least two clutches of eggs. Her latest clutch was produced just prior to the civil war. One of the eggs from that latest clutch was given to Rhaena, Rhaenyra's step-daughter.
In King's Landing Syrax was kept within the walls of the Red Keep in a stable in the outer ward that had been emptied of horses and given over for her use. Heavy chains bound her to the ground. The chains were long enough to allow her to move from the stable to yard but kept her from flying off riderless. The three other dragons belonging to the blacks were kept in the Dragonpit along with the greens's Dreamfyre.
Syrax was slain in the aftermath of the Storming of the Dragonpit.