

Ĭastel had over 200 operatic roles in his repertoire. Over the next 27 years at the Met, he gave nearly 800 performances and later served for three decades, until his retirement in 2009, as its staff diction coach. With the Metropolitan Opera in 1970, he debuted as Don Basilio in Mozart's The Marriage of Figaro. In 1965, he first performed with the New York City Opera as Jacob Glock in The Flaming Angel and performing with that company in numerous roles thereafter. The following month he portrayed Joseph in the world premiere of Carlisle Floyd's Wuthering Heights in Santa Fe. In June 1958 he made his debut with Santa Fe Opera as Fenton in Verdi's Falstaff. He began calling himself "Nico Castel" early in his singing career.

In 1958, he became the first winner of the "Joy in Singing" award, which launched his career with a recital at The Town Hall in New York City.

In the early 1950s, he served in the United States Army as a translator in Germany. After some vocal study in Caracas and then the University of Mainz in Germany, Castel moved to New York City at the age of 16 to pursue a singing career and to study romance languages at Temple University in Philadelphia. He was raised in Venezuela by multilingual parents and a German nanny and attended a French school in Caracas. Castel was born in Lisbon, Portugal, the "scion of a multigenerational dynasty of Sephardic rabbis" with roots in 15th century Castile.
