The piece is known as the Trout because the fourth movement is a set of variations on Schubert's earlier lied, "Die Forelle" (The Trout). Rather than the usual piano quintet lineup of piano and string quartet, Schubert's piece is written for piano, violin, viola, cello and double bass. Dating from 1819, it is the only piano quintet he wrote.
The work is in five movements:
Allegro vivace - as is normal in multi-movement works of the time, this is in sonata form.