PERTANIKA JOURNAL OF TROPICAL AGRICULTURAL SCIENCE

The giant freshwater prawn, Macrobrachium rosenbergii, is an important species in freshwater crustacean aquaculture. Traditional larval feeding methods relying on egg custard are challenged by poor buoyancy and significant nutrient leaching. This study aims to enhance the physical properties of egg custard-based diets by incorporating carboxymethyl cellulose (CMC) and buoyancy modifiers (BM, yeast, and baking powder). Three experimental diets were formulated with varying CMC and BM levels (D1: 5% CMC; D2: 2% CMC & 3% BM; D3: 0% CMC & 5% BM) and evaluated on floatability, water stability, and nutrient retention. The study also involved feeding larvae with these diets and assessing growth performance over several weeks. Assessing the physical properties of each diet over 60 min found that D3 was the most buoyant, achieving a flotation rate of 49.24%, while D2 had a rate of only 32.98%, and D1 20.90%. Water stability assessments showed that D1 retained 70.80% stability after 40 min, compared to 69.55% for D2 and 86.61% for D3. The nutrients of nutrient leaching were not too dissimilar: D1 had a protein retention of 89.00%, D2 a retention at 87.60%, and D3 86.61%. The lipid retention of each diet followed a similar trend, with D1 retaining 90.21% of its lipid content, D2 88.49%, and D3 at 84.47%. This study highlights the importance of optimising dietary formulations for M. rosenbergii larvae, demonstrating that balancing buoyancy and nutrient retention can lead to improvements in the growth and survival of larval cultures. The study concludes that incorporating CMC and BM can enhance diet quality and larval performance.