Rbfox-regulated alternative splicing is critical for zebrafish cardiac and skeletal muscle functions

► Rbfox proteins are regulators of a conserved muscle alternative splicing program. ► Rbfox1l and Rbfox2 regulate partially overlapping networks of alternative splicing. ► Knockdown of Rbfox1l and Rbfox2 causes defects in heart function. ► Knockdown of Rbfox1l and Rbfox2 causes complete paralysis of skeletal muscle. ► Rbfox knockdown causes defects in muscle fiber organization and sarcomere number.