Jannatulhawa Jasni, Nazlina Haiza Mohd Yasin, Mohd Sobri Takriff
Hatcheries mainly grow microalgae on-site to produce high-quality live feed for enriching zooplankton in aquaculture systems, predominantly for the larval stages of aquatic species. However, this is often related to high production and maintenance costs. This has driven research into more cost-effective and practical alternatives, such as freeze-dried or paste forms of microalgae. Therefore, this study aims to evaluate the potential of two local freshwater microalgae of Chlorella sorokiniana UKM3 and Coelastrella sp. UKM4 as an enrichment diet for zooplankton Daphnia magna. C. sorokiniana UKM3 and Coelastrella sp. UKM4 were prior processed into freeze-dried and paste forms. In this study, the commercial Spirulina powder acts as a reference diet and yeast Saccharomyces cerevisiae as the control feed. Results showed that the freeze-dried and paste form of C. sorokiniana UKM3 were the best for cultivating D. magna, promoting high growth, survival, fertility, and longevity. The survival of D. magna fed with paste or freeze-dried forms of C. sorokiniana UKM3 was significantly (P < 0.05) higher than those fed with other microalgae diets. The nutritional profiles of C. sorokiniana UKM3 freeze-dried and paste forms did not vary significantly. The highest protein content was observed in UKM3 Paste (44.2%) and UKM3 freeze-dried (42.9%). The processing of freeze-dried microalgae may slightly lower the quality as compared to fresh algae. However, it still offers comparable nutritional quality and solves the problem related to live algal cultures in aquaculture, which makes them practical for large-scale aquaculture operations.