The combined effects of different densities of Artemia and C/N ratios reared in a biofloc system on growth and biomass production of Artemia were assessed under laboratory conditions. A 3×4 factorial experiment with three levels of Artemia density (500, 750, and 1000 nauplii/L) and three C/N ratios (5, 10, and 15) was randomly designed in four replicates.  Newly-hatched Artemia nauplii were reared in 1.5 L bottles containing 1 L of seawater at 30‰. Molasses with a 38% carbon content was used as a carbon source to stimulate bacterial growth in the Artemia culture medium. The amount of molasses added was based on a concentration of total ammonia nitrogen (TAN) in the culture medium. Results showed that significant interaction effects between Artemia density and C/N ratios were not observed for growth, survival and biomass production. The manipulation of C/N at 5 and 10 promoted better growth of Artemia in terms of length compared to that obtained by Artemia in the higher C/N ratio. However, it was not clear whether there was an increase in growth performance in the culture where Artemia were reared at high densities. Moreover, the addition of molasses produced biomass in stocking density at 500 ind./L that was nearly similar to that obtained in the 750 and 1,000 ind./L.