Effects of restricted feeding rates on growth, production, and economics of Nile tilapia (Oreochromis niloticus) and giant freshwater prawn (Macrobrachium rosenbergii) polyculture in pond-based biofloc and traditional grow-out system

Abstract

The combined effects of restricted feeding rates [50–75% apparent satiation (AS) and 100% AS] and culture systems [biofloc (BFT) and traditional pond system (TP)] on the growth, production, and economics of Nile tilapia-freshwater prawn polyculture were examined in a 2 × 2 factorial feeding trial for 120 days. Each treatment was carried out in triplicate following complete randomized design. Nile tilapia fingerlings (2.09 g) and freshwater prawn post larvae (PL₂₀; 0.05 g) were stocked at an initial density ratio of 6:6 individuals/m². Lower dissolved oxygen (DO) and higher Total Ammonia Nitrogen (TAN) and nitrite concentrations were observed in BFT system. Similarly, higher levels of DO were recorded in 50–75% AS-fed group, while TAN, nitrite, nitrate, and total suspended solids (TSS) were significantly higher at 100% AS-fed group. Culture system, feeding rate, and their interactions had significant effect on final body weight (FBW) and daily growth rate (DGR) of Nile tilapia. Lower FCR in Nile tilapia was noted in both BFT system and 50–75% AS-fed group. For freshwater prawn, the highest FBW and DGR were obtained in BFT system and fed 100% AS. However, survival rates and condition factor did not differ across all treatments for both species. Higher yield for both species and more large-size tilapia were obtained when fed at 100% AS. An increase in yield and significant improvement on the size distribution of prawns were also achieved in BFT system. Although both BFT and 100% AS have led to better performance, cost and return analysis have instead revealed better profitability using TP system and feeding rate of 50–75% AS. The lower cost of production in these treatments has economically compensated for the unfavorable growth, yield, and size distribution.