Density of muscle fibers in the anterior and posterior muscle to the dorsal fin in WT and imbs mutant zebrafish at different developmental stages. The density of the anterior muscles to (i) and posterior muscles(ii) to the dorsal fin in WT and imbs mutant fish were measured at 15 dpf, 30 dpf, 45 dpf, 60 dpf and 75 dpf, data were expressed as mean ± SD of density of muscle fiber. *, P<0.05; **, P<0.01; n.s., no significance.