Abstract: This study was conducted with aim to determine the best C/N ratio for optimum growth performance of Artemia under laboratory conditions. The experiment consisted of four C/N ratios corresponding to 5, 10, 15 and 20 (C-treatments) and a blank treatment used as control; three replicates were involved for each. The C/N ratios were regulated by daily adding molasses into the Artemia culture medium based on TAN concentration, whereas none of molasses was added into the blank treatment. Artemia nauplii (Instar I) were reared in 1.5 L plastic bottle containing 1 L seawater at salinity of 30‰, stocking density was 300 ind./L and maintaining in a room temperature condition with continuously aeration supporting. In the first two days of culturing, Artemia were fed with microalgae Chaetoceros sp., and from the 3rd day onwards to the end of experimental period, Artemia feed (30% of protein and 9% of lipid) was offered as food for the culture. Molasses were added to C-treatments from 3rd day of the culture and since then was daily regulated basing on TAN measurement in the culture medium. After 42 days of culturing, the result showed that the best survival (48 %) and biomass production (4.9 g/L) were obtained in C/N=5 medium, lowest was at control (29.1 %; 3.1 g/L, respectively) and Artemia cultured in C-treatments tend to have better survival as well as biomass production compared to the control. The best growth in length at DAH7 (4.42 mm) and at DAH14 (8.36 mm) was recorded in C/N=10 but there was no significant difference comparing to others.