Water quality from shrimp culture in a nursury phase.

Zooplankton, particularly microalgae-fed species, are optimal candidates for aquaculture nutrition and bioencapsulation vectors. <i>Haematococcus pluvialis</i> is distinguished by its high astaxanthin content in the cystic phase, while <i>Daphnia magna</i> is rich in proteins, fatty acids, chitin, and chitosan—biomolecules with antioxidant and immunostimulatory properties. This study evaluated the dietary supplementation of <i>Penaeus vannamei</i> post-larvae with <i>H. pluvialis</i> bioencapsulated in <i>D. magna</i> (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, <i>H. pluvialis</i> bioencapsulated in <i>D. magna</i> 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.