Clearance rate and feeding of surf clam, Mactra veneriformis were determined for 5 different water temperature regime (5, 10, 15, 20, $25^{circ}C$) and salinity regime (8, 14, 20, 26, 32 ‰) with small group ($86.62{pm}7.10mm$ in shell length) and large group ($147.99{pm}10.83mm$ in shell length). Clearance rate and feeding increased with water temperature up to $20^{circ}C$, but rapidly decreased at $25^{circ}C$. The minimal clearance rate and feedign was recorded at $5^{circ}C$. surf clam showed low clearance rate and feeding at low salinity (below 20 ‰) and maximum values at high salinity (26-32 ‰).