As a zinc finger transcription factor,Sp7 is expressed specifically in osteoblasts.Because Sp7 knockout mice are embryonic lethal,the exact functions of Sp7 in osteoblast and bone formation still are unclear.Here we used TALEN to generate a number of zebrafish sp7 mutants.Unlike mouse,the homozygous sp7 mutant zebrafish are able to survive at least 5 months.We observed that sp7 -/- fish failed to develop opercula,and display curved tail fin and craniofacial malformation.q-PCR results showed that a number of the osteoblast markers were significantly down-regulated in sp7 -/- in comparison with wild-type or heterozygous fish.Together,these results indicate that sp7 is required for zebrafish bone development and these sp7 mutant zebrafish should be invaluable for studying bone diseases in human.