Amino acid profiles of meagre ( Argyrosomus regius ) larvae: Towards the formulation of an amino acid balanced diet

The indispensable amino acid (AA) profile of fish carcass has been commonly used to estimate the AA requirements of fish. In this study the AA composition of whole body tissue of meagre, Argyrosomus regius, was determined at 0, 3, 6, 8, 12, 17, 20, 24, 30 and 39days after hatching (DAH). Several differences were observed during meagre larval ontogeny with the AA profile at 0DAH being different from the remaining larval ages and with a change occurring around 12 and 17DAH which was reflected in some AA such as arginine, valine and tyrosine. Meagre and diet AA profiles were compared and several AAs were found to be in apparent deficiency in the diets. In rotifers a lower number of AA were apparently in deficiency but the correlation between larval and diet AA profiles was low (R2 lower than 0.7). Although a higher number of AA were apparently in deficiency in Artemia and dry feed, the correlations obtained were high (R2 above 0.75). Histidine appeared to be the limiting AA in all diets. These results suggest that the higher nutritional imbalances in meagre larval ontogeny occur during the first 10days of feeding when larvae are fed on rotifers. To solve these apparent nutritional imbalances, an alternative to rotifers should be found or at least a reduction of the period when larvae are fed on rotifers alone. Given the potential of meagre to aquaculture, the use of suitable diets for this species should be formulated. The results obtained in this study can be used to formulate AA balanced diets which are expected to increase growth and decrease larval mortality.