The growth and survival of fan mussel (Pinna nobilis, Linnaeus) juveniles, from natural spatfall, were compared in two groups (large and small size) in Karantina Island Izmir, Turkey, between December 2004 and April 2006. Total live weight, shell length, width and thickness of fan mussel were measured monthly during the study period. Small (32 mm) and large (73 mm) size groups of fan mussel individuals reached 140.25 +/- 10.46 mm and 154.36 +/- 16.12 mm in length and 64.64 +/- 17.98 g and 99.74 +/- 30.53 g in live weight, respectively. Significant differences were found in increases of shell length and live weight. Environmental parameters such as chlorophyll-a, seawater temperature, salinity, particulate organic matter (POM) and particulate inorganic matter (PIM) were determined during each sampling period. Shell length increase was affected by chlorophyll-a and PIM. However, increases in shell length did not correlate with temperature and POM. Survival rates for small and large groups were 93% and 100%, respectively.