Tetsuo Okamoto was a Brazilian born to parents of Japanese heritage, but he attended college in the United States, swimming for Texas A&M from 1956-58. At Texas A&M, Okamoto was a four-time All-American, twice in the 400 and 1,500 freestyle, and won four Southwest Conference titles – 440 freestyle in 1956, and the 220, 440, and 1,500 freestyles in 1957. Prior to his Olympic and college successes, Okamoto had won gold medals at the 1951 Pan American Games in both the 400 and 1,500 freestyle, and had swum for Japan in the 4×200 freestyle relay team (with Ricardo Esperard, Aram Boghossian, and João Gonçalves Filho) that placed second.