The hard clam of difference sizes that from tiny seed to adult will be reared in tanks andraceways of sand absent substrate condition. The live food of microalgae or organismfeed will be supplied to rearing tanks under controlling concentration and rearing waterbe kept overflowing or circulating. The growth and survival rate of different stockdensity in this rearing system be compared to pond culture. The clams under thisculture system will be harvested easily at any stage to transfer other tanks and the uniteproduction will be raised. Moreover, the excellent strains will be selected in fastestgrowth tiny clam seed by this system. Otherwise, the gigantic size clams will be reared inthis system could obtained more economic benefits.