Gilthead seabream - Natural food and feeding habits

Wild seabream have been observed to feed by grazing for prey on rocky surfaces, consuming a variety of prey, with crustaceans, molluscs, polychaetes, teleosts and echinoderms as the major dietary groups (Wassef and Eisawy, 1985; Andrade, Erzini and Palma, 1996). The prey consumed also varies with fish size: juveniles (3–10 cm in length) feed on zooplankton (soft-bodied animals such as polychaete larvae, calanid larvae and other small crustaceans) and even on zoobenthos; bigger fish (>10–25 cm) also consume benthic plants and animals (barnacles, bivalves, polychaetes, amphipods and other finfish) (Wassef and Eisawy, 1985) (Table 1). The trophic level of the gilthead seabream is about 3.3–3.5 (www.fishbase.org). Some studies have also shown gilthead seabream to have a browsing and chewing feeding habit (Andrew et al., 2003).

Digestive system
The terminal mouth is slightly oblique with thick lips. There are four to six sharp teeth in each jaw, followed posteriorly by blunter teeth that become progressively molar-like and are arranged in 2 to 4 rows. The food processing behaviour in seabream may be a consequence of the mouth morphology being suited for browsing. The digestive tract of gilthead seabream consists of an oesophagus, a Y-shaped stomach, few pyloric caeca and the intestine, which narrows from the stomach towards the anus, with two distinct regions, the foregut and the hindgut. The relative length of the intestine is about 1 to 1.1 or less in bigger fish. Adipose tissue is distributed periviscerally in the abdominal cavity, as in many other fish; perivisceral fat deposition can be high in some cases (Figure 2).  The histological and morphological features of the digestive tract of gilthead seabream have been described by Cataldi et al. (1987) and Elbal et al. (2004). The early development of larvae is depicted in Figure 3.