IMPACT OF STOCKING DENSITIES, FERTILIZATION REGIME AND DIETARY PROTEIN LEVELS ON PRODUCTION AND PROFITABILITY OF MONOSEX NILE TILAPIA, OREOCHROMIS NILOTICUS, CULTURED IN PONDS

The relationship between fertilization and dietary protein levels ( 20%, 25% and 30% crude protein) on growth, survival, body composition and upper limit of production were investigated for three different densities ( 5, 10 and 15 fish/m³) of mono-sex Nile tilapia, Oreochromis niloticus, juveniles. The results showed that by increasing stocking density the growth performance significantly decreased (P<0.05), however, with fertilization this pattern demonstrated a positive relationship between density and final yield of O. niloticus juveniles with the increase of dietary protein level. Moreover, feed utilization and survival significantly increased (P< 0.05) in fertilized ponds regardless to dietary protein levels. However, feed conversion ratio (FCR), protein productive value (PPV), and protein efficiency ratio (PER) significantly improved with applying fertilizers in ponds in all stocking densities. Meanwhile, when increasing dietary protein level the PPV and PER where significantly decreased (P< 0.05). Consequently, with density 15fish/m³ and 20% crude protein the FBW, WG, and ADG were significantly low with unfertilized ponds, while the opposite was observed with low density in fertilized ponds. In addition, the final total yield produced was significantly increased with the increase of fish density per cubic meter in the presence of fertilization, and increased insignificantly with the increase of dietary protein level. Thus, the economic assessment revealed that fertilization resulted in the possibility of using low dietary protein levels, and so increased the total outcome profit. Also, high density prompts the increased of total yield per feddan which resulted in a significant high profit return per capita. Finally, the present study advises using high stocking density per cubic meter with fertilized ponds and low dietary protein levels for O. niloticus juveniles.