Growth dynamics and resource partitioning in Oreochromis niloticus and Clarias gariepinus polyculture: Deciphering species ratios and density regimes in concrete ponds

Abstract

A controlled three-factor experiment was conducted to investigate the effects of culture system (monoculture vs. polyculture) and stocking density on the growth performance, feed utilization, and survival of Nile tilapia (Oreochromis niloticus) and African catfish (Clarias gariepinus) fingerlings in indoor concrete ponds under limited water-exchange conditions. Seven treatments combining species composition (1T:0C, 0T:1C, 1T:1C, 2T:1C, 3T:1C, 1T:2C, 1T:3C) and four stocking densities (12, 24, 36, 48 fish/m³) were applied, each with three replicate ponds. Fingerlings (15.02±0.4 g tilapia; 25.23±1.3 g catfish) were cultured for sixteen weeks. Data were analyzed using one-way ANOVA followed by Fisher’s Least Significant Difference (LSD) test at P<0.05, which revealed significant effects of culture system and stocking density on all measured parameters. Polyculture treatments with balanced species ratios (1T:2C and 1T:3C) optimized growth, feed conversion efficiency, and total yield for both species, whereas tilapia monoculture favored tilapia growth only at lower densities. Survival rates remained high across all treatments (91.7-100%), with lower densities supporting slightly higher survival due to reduced competition and social stress. Total biomass increased linearly with tilapia proportion, with maximum tilapia yield in 3T:1C (4391 g/m3) and maximum catfish yield in 1T:2C and 1T:3C (3609 and 4991 g/m3, respectively). These results indicate that strategic species combinations and intermediate-to-high stocking densities can significantly enhance growth, feed utilization, survival, and total yield, providing practical guidelines for sustainable, biosecure, and economically viable indoor aquaculture systems.