The freshwater cladoceran Ceriodaphnia quadrangula has good potential for mass culture as live food for fish larvae due to wide tolerance range to water temperature and light regimes as well as its culture using microalgal species. This research aimed to investigate the combined effect of different light regimes and microalgal diets on growth, production, fecundity and fatty acid composition of C. quadrangula. Three separate experiments were carried out under laboratory conditions. In first experiment, effect of four light regimes including of 4L: 4D (4 hours light: 4 hours dark), 6L:6D, 8L:8D, and 12L:12D, and two green mono-algal diets of Scenedesmus quadricauda and Chlorella vulgaris, were examined on growth and production of C. quadrangula in a completely randomized designs with six replicates. In second experiment, similar treatments (as described for first experiment) were carried out at individual levels for measuring fecundity. In the third experiment, C. quadrangula were mass-cultured with the most suitable light regimes of 6L: 6D and 12L: 12D, which found out from first and second experiments, suing similar algal diets. Results showed that population density, specific growth rate ( SGR ) and doubling time ( Dt ) were significantly different among the treatments (P 0.05). The highest mean population density of C. quadrangula fed on S. quadricauda were 1000 ± 50.9 (Mean ±standard error), 571.4± 57.3, 690.5 ± 62.3, and 1000 ± 58.7 individuals/L at 4L: 4D, 6L:6D, 8L:8D and12L:12D, respectively. Correspondingly, when using C. vulgaris as a diet the values were 1642.9 ± 46.0, 2261.9 ± 72.2, 1023.8 ± 75.0 and 2619.1 ± 80.3 individuals. L -1 . In addition, mean SGR obtained in different treatments were ranged from 0.04 to 0.11 day -1 . The highest mean of length (833.3±59.3 µm), width (553.3±28.8 µm), and weight (6.8 ±1.1 µg) of C. quadrangula adult were obtained at 4L: 4D light regime and C. vulgaris as the diet. The maximum fecundity of 3 ind./female was obtained at light regime of 6L:6D when fed S. quadricauda . Mass culture of C. quadrangula at 6L:6D and 12L:12D produced 2466.7±79.72 and 2350±74.5 ind./L fed on S . quadricauda and 1483.3±46.7 and 1666.7±46.1 ind./L fed on C. vulgaris , respectively. Results showed that the fatty acid compositions under light regimes and algal diets were significantly (P 0.05) changed. The SAFA (saturated fatty acid), MUFA (Mono-unsaturated fatty acid) and PUFA (Poly-unsaturated fatty acid) of C. quadrangula at 6L:6D were 28.5±1.5%, 29.6±1.0%, and 34.1±1.6% of total fatty acid when fed S. quadricauda and 36.5±2.1%, 33.1±1.2% and 27.5±1.9% when fed C. vulgaris , respectively. Correspondingly, the amount of fatty acid at 12L: 12D were 35.2±1.9 %, 26.2±0.9%, and 28.4±1.9% of total fatty acid when fed S. quadricauda and 30.6±1.6%, 30.1±1.1% and 33.4±2.3% when fed C. vulgaris , respectively. Of SAFA, C16:0 had the highest percentage (22.1 %) at 12L: 12D fed on S. quadricauda while the highest percentage of MUFAs were C18:1n-9 (14.9%) and C18:1n-7 (9.0 %) at 6L: 6D when fed C. vulgaris and S. quadricauda , respectively. As for the PUFA, the highest mean ranges of fatty acids were observed with C18:2n-6 (9.8-20.2%) and C18:3n-3 (6.9-16.0 %) in different combinations of light regimes and algal diets. .Based on growth, production, and fatty acid composition, it is concluded that C. quadrangula could be cultured on different light regimes and algal diets, but the suitable culture conditions of 12L: 12D and 6L: 6D showed a better performance. Key words: Light regimes, Ceriodaphnia quadrangula , Microalgae, Fatty acid composition, Production, Growth