Myostatin(Mstn)is a negative regulator of mammalian muscle growth.Though it has duplicated copies of mstn in fish,little is known whether it controls muscle growth in fish.Yellow catfish(Tachysurus fulvidraco)is one of the most important freshwater aquaculture species in China.Previously,we knocked out mstna in yellow catfish using zinc finger nuclease.To uncover roles of mstn genes in yellow catfish muscle growth,we performed targeted disruption of the second mstn,namely mstnb,in yellow catfish.