Erik was a member of national swimming team A and represented Czech Republic on various international events.
In 2003 Rajohnson became a member of Madagascar national swimming team and debuted his new career on African Island Games (JIOI) with three medals in Breaststroke and Individual Medley.
In 2007 year Erik took first Madagascar's gold medal (and another two silver) in swimming on African Island games (JIOI) in men's 200m breaststroke course and has been invited by FINA to participate on Beijing 2008 Summer Olympics.
Rajohnson was invited by FINA through the Universality rule to compete for Madagascar in the men's 100 m breaststroke at the 2008 Summer Olympics in Beijing.
He continued with swimming until his retirement from the sport in 2011 to focus on his stint as an international business development project manager for bilingual languages (French and English).