 Ziska won the Nordic Junior Chess Championship in 2006 for boys born in 1989 and 1990.In 2007 he took bronze and in 2008 he took silver together with Høgni Egilstoft Nielsen at the Nordic Junior Chess Championship.In 2009 he became Nordic Junior Champion in the oldest age group at the competition which was held in Ziska's hometown Tórshavn that year.