Evaluation on Microencapsulated Feed for Pseudosciaena Crocea Larvae Based on Particle Size and Stability of Granules in Water

Particle size and stability in water of a microencapsulated feeding material for larvae and juveniles of Pseudosciaena crocea were studied in relation to the net energy gain of the fish, the water quality of the aquaculture pond, and the survival rate of the young seedlings. Size distribution and reductions on average volume and median diameter, D₅₀, of the particles after submerging in seawater were used to evaluate the suitability for fish feeding and the granule stability of feed. A laser particle size analyzer was applied for the measurement of 4 microencapsulated feed granules, which had been verified to be microcapsules by SEM morphology. The body size of 12-day-old yellow croaker larvae and the microscopic images of 5-day-old larvae fed on the microencapsulated silage were recorded for comparison. The particle size and size distribution of all four feed samples were found adequate for the feeding. In particular, Sample A2 had a D₅₀ of 71.63-61.92 μm with a 12.15% volume reduction and 19.19% D₅₀ decrease after suspended in seawater for 120 min, indicating its potential in meeting the requirements for feeding larvae and juveniles of P. crocea. Furthermore, the wet laser particle size analyzer was considered adequate for measuring the particle size and size distribution as well as predicting the stability of microencapsulated granules in water.