Effect of Concentration and Frequency of Feeding with Food (Fermented Rice Bran) on Mass Culture of Natural Copepod

Development of natural copepod production using fermented rice bran at different concentrations and feeding frequencies was studied. The experiment followed a factorial design with two factors: rice bran concentration (50, 100, and 150 ppm) and feeding frequency (first feeding only and second feeding on day 4 after the first feeding). The experiment was conducted in 18 plastic buckets of 10-liter capacity for a duration of 30 days. The results showed that copepods responded to the increase and decrease in density in the same direction. The interaction between the two factors (rice bran concentration and feeding frequency) showed a significant influence on the copepod density (p<0.05). The highest copepod densities were observed when using first feeding only at a high rice bran concentration of 150 ppm (Mean±SE) of 6.4±1.4a ind./ ml. For the second feeding on day 4 after the first feeding, copepod densities were lower for all concentrations: (Mean±SE) 2.7±0.4, 2.4±0.3, 2.1±0.5 ind./ ml respectively. The most abundant types of copepods were from the orders Calanoid, Cyclopoid, and Harpacticoid copepod with percentages of 64.9, 23.3, 11.8 ind./ml, and the copepod stages were represented by nauplii, adult, copepodite, the adult with eggs. Their percentages were 38.9±2.0, 37.0±1.7, 23.6±1.4, 0.5±0.2 ind./ml, respectively. It can be concluded that using fermented rice bran at a high concentration of 150 ppm with the approach of first feeding only is sufficient enough to increase the mass culture of natural copepods.