For a long time, farmers have overlooked the fact that an Artemia nauplius is not feeding in its first stage of development and thus consumes its own energy reserves. At the high water temperatures which are applied for cyst incubation, the freshly hatched Artemia nauplii develop into the second larval stage within a matter of hours. It is important to feed first-instar nauplii to the predator rather than starved second-instar metanauplii, which have consumed 25 to 30% of their energy reserves within hours. Instar II Artemia are less visible, as they are transparent, and they are larger and swim faster than first-instar larvae, as a result of which they are less acceptable as prey. Furthermore, they contain lower amounts of free amino acids, so they are less digestible and their lower individual organic dry weight and energy content will reduce the energy uptake by the predator per hunting effort. All this will be reflected in reduced growth of the larvae and an increased Artemia cyst bill (as about 20 to 30% more cysts need to be hatched to feed the same weight of starved metanauplii to the predator). Molting of the Artemia nauplii to the second-instar stage may be avoided and their energy metabolism greatly reduced by storage of the freshly hatched nauplii at a temperature below 10^°C in densities of up to 8 million nauplii per liter, for periods up to 24 h. A slight aeration is needed in order to prevent the nauplii from accumulating at the bottom of the tank, where they would suffocate. By applying 24-h cold storage (using styrofoam-insulated tanks and blue ice packs for cooling), commercial hatcheries are able to economize their Artemia cyst-hatching effortst (e.g., fewer tanks, bigger volumes, maximum one hatching and harvest per day). Furthermore, cold storage allows the farmer to ensure the availability of a better quality product and, at the same time, to consider more frequent food distributions. This appears to be beneficial for fish and shrimp larvae, as food retention times in the larviculture tanks can be reduced and hence growth of the Artemia in the culture tank can be avoided. With poor hunters such as the larvae of the tiger shrimp Penaeus monodon, feeding cold-stored Artemia results in much more efficient food uptake (Dhont et al.,1993).