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Settling velocity and total ammonia nitrogen leaching from commercial feed and faecal 50Several studies under laboratory conditions reported that 250-300 g kg -1 of ingested food is 51 voided as faeces (Butz and Vens-Cappell, 1982). Just as with food losses, a continuous 52 4 improvement in diet elaboration has led to a gradual reduction of faecal discharges to about 53 100-250 g kg -1 of ingested food (Cho et al., 1994; Talbot and Hole, 1994 Watling, 1994; Elberizon and Kelly, 1998; Chen et al., 1999a,b; Chen et al., 2003) MRAs for feed pellets (Table 3) showed that water temperature and pellet density had no (Table 5). Constant k was significantly higher at 25 ºC (P < 0.05) and in smaller feed pellets 215 (P < 0.05), while t a was significantly larger at 15 ºC (P < 0.05) but also for smaller pellets (P 216 < 0.05) ( 246The influence of pellet weight was also identified by other authors (Elberizon and Kelly, 247 1998; Chen et al. 1999b, Sutherland et al., 2006. In this study, we not only found that initial 248 pellet size determined settling velocity but also, unlike Chen et al. (1999b) authors state, the range of parameters studied was not so critical to the settling velocity. 270Despite this, we observed greater but non significant settling velocities at low temperature, as 271 Chen et al. (1999b) noted. These authors suggested that this could be due to the influence of 272 temperature on pellet density, although in our experiments we found that seawater 273 temperature did not affect pellet density.

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