<![CDATA[Chaetoceros calcitrans is one of the diatoms commonly used as a natural feed for cultivated fish larvae. The cultivation of C. calcitrans as natural feed is influenced by various factors, including light as a source for photosynthesis. This research aimed to determine the effect of different light colors on the growth rate and identify the optimal color for the growth rate of C. calcitrans. The research was conducted at the BPIU2K Karangasem laboratory. The experimental method with a Completely Randomized Design (CRD) was employed, consisting of three treatments and one control. Treatment A used yellow-colored lights, treatment B used blue-colored lights, treatment C used green-colored lights, and treatment D served as the control using white-colored lights. The observed parameters included population density, specific growth rate, and doubling time. The results were analyzed using ANOVA. The findings indicated that the light color significantly affected the population density, specific growth rate, and doubling time with a value of (Sig.<0.05). The best treatment was the use of white-colored lights, followed by yellow-colored lights, which resulted in the highest density on the 5th day, reaching 1.238,88 x 104 cells/ml and 1.040,55 x 104 cells/ml, respectively. The specific growth rate for white and yellow lights was 8.51%/hour and 7.53%/hour, respectively. The doubling time for white and yellow lights was 14.93 hours and 15.75 hours, respectively. White and yellow light irradiation exhibited wavelengths suitable for the cultivation of C. calcitrans.]]>
