He was an organizer of jazz performances and an important participant in the musical life of the Theresienstadt concentration camp.

[2] As a member of the Karel Ludvík Orchestra, Weiss became a bandleader and helped to organize rehearsals, but above all, he arranged the major part of the repertory of the ensemble.

[1][4] With the help of Czech police officers he managed to obtain music paper and scores needed for arranging jazz compositions.

Both bands collaborated in various performances and the number of musicians increased, especially following the arrival of Danish and Dutch Jewish jazz players.

[6] Weiss, together with Berlin pianist Martin Roman, composed and arranged more than thirty new compositions for the ensembles.

The most popular composition was the jazz arrangement of the children's opera Brundibár, originally composed by Hans Krása.

[7] In June 1944, during the visit of the Red Cross to the camp, the Ghetto Swingers were forced to participate in the propaganda performance organized by Kurt Gerron, coerced by the Germans to deceive the outside world.