|Initial mean mass (g)||79.1±5.0|
|Final mean mass (g)||124.2±7.8||133.5±12.1||130.7±12.1|
|SGR (% day)||0.92±0.13||1.04±0.19||0.92±0.22|
|Hepatosomatic index (%)||1.14±0.09||1.11±0.13||1.15±0.08|
|Faecal [Fe] (μmol g—1 d.m.)||3.4±1.1a||12.3±3.5b||45.1±2.9c|
|Final whole body Fe content (μmol fish—1)||28.4±2.5a||27.6±2.2a||95.1±6.7b|
|Apparent net Fe retention (%)||23.2||4.1||2.7|
Values are mean ± s.e.m. At the end of the experiment, week 8, N=21 fish per treatment, except faecal Fe N=6, and whole body Fe content, N=9. Specific growth rate (SGR) and mean fed conversion ratio (FCR) were calculated from the mean mass gain/treatment between weeks 2 and 8. Whole body Fe contents are calculated from mean fish mass/treatment over the duration of the experiment and whole carcass Fe concentrations in Table 1. Whole body Fe content of initial fish was 17.7±0.9 μmol fish—1. Apparent net Fe retention = (final carcass metal content — initial carcass metal content/metal consumed)×100%. Proximate composition is expressed as a percentage of dry matter (mean± s.e.m., N=9 fish per treatment for moisture and N=3 tanks per treatment for pooled analysis of protein, lipid and ash. Initial fish moisture, protein, lipid and ash, respectively, were (% dry matter, mean ± s.e.m., N=6 fish per treatment for moisture and N=3 tanks per treatment for other parameters): 72.1±1.90, 57. 6±0.4, 18.1±0.4, 12.0±0.2%. No differences were observed in SGR, FCR, condition factor, HSI or proximate composition between initial and final fish (Student's t-test, P>0.05). Different letters indicate significant differences within rows (t-test, P<0.05).