Under farming conditions, following the mouth opening (days 3 to 5 post-hatch), initial feeding is done with rotifers (0.15 to 0.25 mm); larvae are subsequently fed Artemia nauplii, which are also normally enriched using different commercial enrichment media, after which they are “weaned” with micro-particulate compound formulated feeds once they attain a body weight of about 20 to 50 mg (one month at 20 °C).

The rough scheme for the production of larvae is as follows:

An example of a feeding sequence of live feeds is given in Table 3. As with other marine finfish, much effort has been put towards reducing some sequences, such as feeding rotifers and reducing the duration of total feeding with live prey through co-feeding or “weaning” to dry particulate feeds at an early date. It is not uncommon these days to have the whole sequence reduced to less than 40 days instead of more than two months, which was prevailing earlier. The proximate/nutrient composition of live prey can vary considerably, and both rotifers and Artemia are enriched with different enrichment media to improve their nutritional values.

Much work has also been undertaken to develop microdiets for gilthead seabream larvae, and some progress has been made to develop formulated complete feeds for rearing these larvae right from the first feeding onwards (Yufera, Pascual and Fernandez-Dias, 1999; Yufera, et al., 2000; Pousão-Ferreira et al., 2003; Robin and Vincent, 2003; Seiliez et al., 2006). A few examples of larval microdiets are given in Table 4. However, despite reasonably good survival and larval growth, overall performance of gilthead seabream larvae fed such inert formulated diets is lower compared to that of those fed live prey from first feeding. It is, however, essential to develop a microdiet to reliably estimate the nutrient requirements as well as the physiological responses of larvae to specific nutrients.

Feedstuffs of both marine and plant origin are used in the formulation of feeds for the gilthead seabream. As regards protein sources, in Europe, processed animal products are not commonly used.  A short list of major ingredients used as protein/amino acid sources and their nutritional values are provided in Table 6. With regard to fatty acid sources, a list of oils and their major fatty acid profiles are given in Table 7.

A number of formulae are used by feed manufacturers, using the general nutritional constraints presented in Table 2. The feeds are formulated by the individual feed manufacturers using one of several least-cost formulation software programs. They generally contain a mixture of different protein/amino acid sources, fatty acid sources, vitamins, minerals and trace elements. The micronutrients are generally included in the form of premixes (Tables 8 and 9).  In recent years, much progress has been made in reducing the level of fishmeal in the feeds for gilthead seabream (Gomez-Requeni et al., 2004). Feed formulae are generally determined by nutrient availability and digestible energy levels. Some data on the apparent digestibility coefficients (ADC) of selected feed ingredients estimated in gilthead seabream are reported in Table 10. A few feed formulae used at a large scale to demonstrate the possibility of reducing the fishmeal levels and on replacement of fish oil by a mixture of vegetable oils are reported (Tables 11 and 12).

A number of commercial additives are available that are used to a greater or lesser extent by different feed manufacturers; these include mould inhibitors, immunostimulants and pre- or probiotics. Addition of phytase in feeds containing phytic acid-rich plant ingredients has been found to be beneficial in improving phosphorus availability in gilthead seabream (Güthler, 2005). Given that pigmentation of the head and opercular area of gilthead seabream are criteria of quality, some studies have shown the possibility of improving this trait through dietary pigments derived both from natural and synthetic sources (Gomes et al., 2002; Gouveia et al., 2002).

Larval feeds are distributed using belt feeders or other specially developed feed dispensers. In cage culture operations, both hand feeding based on feeding tables provided by feed manufacturers (Table 13) and using mechanical feed distributors occurs. Commercial cage farms use both hand feeding as well as automatic feeders combined with video monitoring of feeding behaviour.