Flocponic technology uses carbon to create value-added products, contributing to aquaculture’s economic diversity and sustainability. Carbon products promote microbial floc, which controls fish disease and reduces nutrient discharges. The availability, low cost, and chemical composition of agricultural carbon sources make ideal substrates for flocponic application. The study evaluated how agricultural carbon sources affect flocponic Nile tilapia and rice growth, water quality, and the economic viability of flocponic production. A complete randomized design was employed in five treatments (wheat-bran, Rhodes-hay, maize-cob, maize-stables, luceme-hay) and control (no carbon source), each in triplicate. Each treatment and control had Nile tilapia and rice densities of 98 fry m3 and 250 rice m2, respectively. Fish weight and length trends varied significantly between treatments and control (p < 0.001). The lucerne-hay had the highest final weight (2.94 ± 0.15 g), length (7.52 ± 0.08 cm), SGR (2.80), and weight gain (2.67 g), whereas the control had the lowest. The FCR was highest in the control (1.12) and lowest in the luceme-hay. Rice growth parameters differed significantly (p < 0.05) between treatments and control. The lucerne-hay had the highest rice tillers (1.28± 0.04), leaves (0.84 -£ 0.02), heights (34.59 ± 0.83 cm), grain weight (189.82 ± 5.20 g), and stable weights (346.60 ± 43.5 g), while the control had the lowest. The water parameters (dissolved oxygen, temperature, and TDS) did not differ between treatments and control (p > 0.05). Ammonia, nitrite, nitrate, soluble reactive phosphorus (SRP), pH, and electrical conductivity differed (p < 0.05) between treatments and control. The luceme-hay had the lowest ammonia (0.27 ± 0.02 mgL-1), nitrite (0.25 ± 0.01 mgL-1), and the highest nitrate (0.91± 0.06 mgL-1) and SRP (0.642 ± 0.05 mgL-1) levels. The flocponic system’s profitability varied between the treatment and control. Lucerne-hay (KES 1338.39) generated the highest positive net income, followed by wheat-bran (KES 474.69) and Rhodes-hay (KES 266.1). The return on investment was positive in lucerne-hay (72.19), wheat-bran (25.13), and Rhodes-hay (14.39). The simple sugars and solubility nature of wheat-bran, luceme-hay, and Rhodes-hay have directly or indirectly improved flocponic rice, fish growth, and water quality. The study concludes that wheat-bran, lucerne-hay, and Rhodes-hay are the best carbon sources and most economically viable for flocponic production and are therefore recommended for small-scale farmers.