Introduction:
Giant grouper, Epinephelus lanceolatus, a species already successfully farmed in aquaculture in the Pacific region, appears ideally suited for RAS aquaculture in Europe because of its good growth performance, known reproduction and market potential. However, for successful cultivation in RAS, reliable and site-adapted data must be available. Preliminary studies were carried out for future commercial cultivation in closed facilities and economic calculations for the species were performed for Germany. An important aspect is the identification of formulated feeds that meet the requirements of the species and can be purchased in Europe. In addition, it is necessary to determine an optimal rearing density at which the animals can grow in an economically viable manner while optimizing animal welfare.
Material and methods:
For the feed trial, commercially available feeds in Germany were tested. 3 basically suitable feeds with different protein/fat ratios were selected for the trial. Feed 1: 42/13, Feed 2: 54/14, Feed 3: 55/17. Juvenile grouper (61.5 ± 6.9 g) were fed ad libitum in replicate (4) four times daily for 35 days. At the end of the experiment, growth- and blood parameters and body composition were determined. In a second experiment, juvenile grouper (437.4 ± 40.3 g) were kept in quadruplicate tanks for 8 weeks at different stocking densities - low: 60 kg/m³, medium: 80 kg/m³, high: 100 kg/m³. Growth, stress parameters and external appearance were determined regularly.
Results and conclusion:
Results showed that 2 of the 3 tested diets, appear suitable in principle for giant grouper (table 1). Growth was comparable to previous studies using optimized diets Lin / Yeh (2022). However, insufficient protein content has a negative effect on the animals. In addition, it was shown that the tested rearing densities had no effect on growth, stress and external appearance in the trial. These data, together with production data of existing giant grouper aquacultures and site-specific financial and market data, confirm that the giant grouper appears suitable for cultivation in RAS in Europe.
Lin, Y.-H., & Yeh, C.-C. (2022). Effects of dietary lipid levels on growth, lipid deposition, oxidative stress and hepatic morphological changes in giant grouper, Epinephelus lanceolatus. Aquaculture Research, 53, 2431– 2438. https://doi.org/10.1111/are.15760