Daphnia fed with Chlorella and Haematococcus in cystic phase.

Zooplankton, particularly microalgae-fed species, are optimal candidates for aquaculture nutrition and bioencapsulation vectors. Haematococcus pluvialis is distinguished by its high astaxanthin content in the cystic phase, while Daphnia magna is rich in proteins, fatty acids, chitin, and chitosan—biomolecules with antioxidant and immunostimulatory properties. This study evaluated the dietary supplementation of Penaeus vannamei post-larvae with H. pluvialis bioencapsulated in D. magna (DHP), comparing it to a commercial supplement (CS) and a control diet (C). Water quality, growth performance, histology, nutritional composition, hematology, and key bioactive compounds (total carotenoids, astaxanthin, chitin, and chitosan) were assessed. Water quality remained stable across treatments. Growth performance and protein content were higher in DHP and CS groups, though DHP exhibited lower lipid levels. The DHP diet enhanced the shrimp's immune response, evidenced by the highest total hemocyte count (THC). Additionally, DHP yielded greater chitin, total carotenoids, and astaxanthin concentrations. Histological analyses revealed increased B-cell numbers in the hepatopancreas of shrimp from DHP and CS treatments. Thus, H. pluvialis bioencapsulated in D. magna supports growth comparable to a commercial supplement while enhancing immune markers and bioactive compound levels. These findings highlight its potential as an alternative protein source for sustainable shrimp nutrition. Further investigations into enzyme activity, gene expression related to protein and lipid digestion, and additional immune parameters would provide deeper insights into its effects on shrimp physiology.