"All I Do Is Think Of You"

Chico was the eldest of the Marx Brothers, but the youngest of them when he died (age 74) in 1961. 

Chico was a talented pianist. He originally started playing with only his right hand and fake playing with his left. As a young boy, he gained jobs playing piano to earn money for the Marx family. Sometimes he worked playing in two places at the same time. He would acquire the first job with his piano-playing skills, work for a few nights, and then substitute Harpo on one of the jobs. (During their boyhood, Chico and Harpo looked so much alike that they were often mistaken for each other.)

Groucho Marx stated that his brother got the name Chico because he was a "Chicken-chaser" (early slang for chasing women). He also said that Chico never practiced the pieces he played. Instead, before performances he soaked his fingers in hot water. He was known for 'shooting' the keys of the piano. He played passages with his thumb up and index finger straight, like a gun, as part of the act. 

For a while in the 1930s and 1940s, Chico led a big band. Singer Mel Tormé began his professional career singing with the Chico Marx Orchestra.

Here he plays "All I Do Is Think Of You" in A Night at the Opera (1935), for a group of delighted children. 

[Watch how the Hollywood power game was being played, even by children, back in 1935. At the start of this piece, a small boy takes his place next to the piano. A much larger kid makes his way over, then muscles in, displacing the little kid.]