The study describes growth and survival on different kinds of sediment improvements of early spats of the hard clam, Meretrix petechialis. Specimens of the mature hard clam were collected in the intertidal zone of Yeonggwang, Korea, July 2011. After transportation, early spats(shell length 196 ± 14 μm) collected in mature hard clam were used. Experiment period were July 7 to August 6 in 2011 (30 days). Sediment improvements used iodine(10 ppm), hydrogen peroxide(H2O2, 5 ppm), sodium hypochlorite (NaClO, 100 ppm), chlorine dioxide(ClO2, 100 ppm) and potassium permanganate (KMnO4, 5 ppm). After cultured during 30 days, shell length growth of hard clam were observed 1.04 ± 0.26 mm in sodium hypochlorite 100 ppm, 1.03 ± 0.25 mm in chlorine dioxide 100 ppm and 1.01 ± 0.28 mm in iodine 10 ppm. Survival rate were 31.4% in chlorine dioxide 100 ppm, 12.1% in sodium hypochlorite 100 ppm, 11.6% in iodine 10 ppm, 1.5% in hydrogen peroxide 5 ppm and 0% in potassium permanganate 5 ppm.
