He was last Spartocid ruler of the Bosporan Kingdom and ruled from 125 to c. 109 BC after the death of his brother Paerisades IV Philometor.

The kingdom had been under increasing pressure from the nearby Scythians, probably under the rulers Skilurus and Palacus.

His elder brother may have been killed by the Scythians, as well as a probable relative named Spartokos VI, though his existence is disputed.

Towards the end of Paerisades's reign, Diophantus, a general in the service of Mithridates VI of Pontus, began attacking the Scythians under Palacus and then made his way to the Bosporan Kingdom's capital of Panticapaeum.

There, he entered into talks with Paerisades to bring the Bosporan Kingdom under the control of Mithridates VI in exchange for his survival.