idefix mutants show defects in pigment pattern formation. Wild-type (A,A′) zebrafish show a stereotypic pattern of horizontal dark and light stripes on their flanks and on the anal and caudal fins. In ide mutants (B,B′) the light stripe areas are expanded, there are fewer and less regular dark stripes, which frequently show interruptions. The striped pattern in the anal and caudal fins is also disrupted in ide mutants. Double mutants of ide with leo (C-D′), luc (E-F′) or obe heterozygous (G-H′) and homozygous (I-J′) show a superimposition of both phenotypes. The light stripe areas are expanded in all cases. Scale bars: 5mm J, 1mm in J′.