Nikishyn took up fencing at the age of ten after he came by chance to a fencing training. He won a team silver medal at the 1998 Junior World Championships in Keszthely and joined the senior national team for the 2001 World Championships in Nîmes. He took part in the 2004 Summer Olympics, but was eliminated in the preliminary round by Romania's Alexandru Nyisztor. In the team event Ukraine was defeated in the first round by Hungary and finished 5th after the placement rounds.