This work investigates the factors controlling production and determines the biophysical properties of cross-linked protein coated microencapsulated diets, with a view to enhancing their acceptability and digestibility to omnivorous and carnivorous larvae. To estimate optimal feed larvae of Penaeus monodon on microencapsulated diets, facilitate live transportation and add to the biological knowledge of the species, the relationship between metabolic rate/temperature and energetics of the larval stages were investigated. Also described, are laboratory growth and survival trials with P. monodon larvae fed on cross-linked protein microencapsulated diets. Success with P. monodon larvae, led to investigations on acceptability, growth and energetics of juvenile P. monodon reared on an artificial diet. For comparison, a similar line of approach was adopted with the carnivorous larvae of Homarus gammarus. Studies on the physiological energetics of the larvae were followed by investigations on acceptability, growth and digestibility of artificial diets fed to H. gammarus larvae. The final discussion attempts to correlate the contrasting larval growth/survival results to the different energy strategies adopted by the larvae.