Also, during that time, he was a member of the Lamas Choir and for fifteen years, Interpreter (Principal Pianist) of the Venezuela Symphony, an orchestra that he also conducted on multiple occasions.

As a pianist he imposed a brilliant style that was expressed not only in more than 40 years of concerts but also in his compilations and harmonizations of the Venezuelan dances and waltzes of the nineteenth-century and the recording an important number of albums.

He also performed as accompanying pianist with world-class musicians such as Mstislav Rostropovich, Henryk Szering, Maurice Hasson, Adolfo Odnoposoff, Florian Ebersberg among others.

As a performer, he also excelled as an organist, ending his career with two organ concerts at the cathedrals of Notre Dame in Paris and Chartres Cathedral in France, in 1975 His orchestral works have been performed and recorded in countless countries around the world such as Venezuela, Brazil, Uruguay, Argentina, Mexico, United States, Spain, France, Germany, Austria, Holland, Poland, China, Korea or Japan, among others.

His brother, Gonzalo Castellanos Yumar, is a notable organist, composer and former chief conductor of the Venezuela Symphony Orchestra (1966–1978).