The nutritional effectiveness of a food organism is first determined by its ingestibility and, as a consequence, by its size and form. With the exception of Penaeus spp. larvae, which are phytoplankton feeders initially, most decapod larvae can be reared on Artemia nauplii for their complete development. As long as prey size does not interfere with the ingestion mechanism of the predator, the use of larger nauplii (with a higher individual energy content) will be beneficial, since the predator will spend less energy in taking up a smaller number of larger nauplii to fulfill its energy requirements (Dhont et al.,1993).