When she was 12 years old, Tandon was spotted at a state meeting, and was selected to compete in two national events, and won a bronze medal. Tandon went on to compete in the
Asian Games at the age of 13, and her first World Championship at 16. She won five individual gold medals in the competition, and was declared best swimmer for the third consecutive year. At the
2004 Athens Olympics, Tandon competed in both the 50 m and the 100 m
freestyle, the first Indian swimmer to qualify for two separate events in an Olympic competition. In 2005, Shikha held seven national records, and was the first Indian woman to hold so many simultaneously. In the same year, she became the first female Indian to win an international medal for a short-course event, taking bronze at the indoor Asian age-group swimming Championships in Bangkok. In 2009, after completing her dual master's degree in Biology and Biotechnology from Case Western Reserve University, she applied at the USADA, and became the first Indian to be employed at the USADA. == Personal life ==