Impact of Feeding Strategies on Trophic Dynamics, Growth Performance and Sustainability of Nile Tilapia in Semi‐Intensive Aquaculture Systems

Abstract

ABSTRACT Feed costs and limited knowledge of feeding strategies are a major constraint to the sustainability of semi‐intensive Nile tilapia aquaculture systems in sub‐Saharan Africa. In semi‐intensive systems, Nile tilapia ( Oreochromis niloticus ) utilizes natural pond production and supplemental feed, but their relative contributions to growth remain unclear. A 90‐day pond experiment assessed the effects of feeding regimes on Nile tilapia trophic dynamics and growth. Fingerlings (5.6 ± 0.14 g) were stocked at 3 fish m −2 in 15 ponds and assigned to five treatments: low (1%), medium (2%) and high (4%) feeding under standard fertilization and two double‐fertilized treatments with continuous low feeding (DF/L) or delayed feeding (DF/2N/1M; no feed for 60 days, then 2% for 30 days). Diet composition was assessed using δ 1 3 C and δ 1 5 N mixing models. Growth did not differ among treatments in the first 2 months but diverged in the last month. Delayed feeding combined with fertilization (DF/2N/1M) resulted in superior growth performance, efficient feed utilization and limited physiological stress compared to continuous feeding. Stable isotope analysis showed that fish in M, DF/L and DF/2N/1M fed mainly on zooplankton with limited detectable feed assimilation based on endpoint muscle isotope signatures. H fish consumed mostly sediment organic matter, whereas L fish had a mixed diet of feed, zooplankton, zoobenthos and sediment. These findings align with earlier stomach content studies showing tilapia <80–100 g rely primarily on secondary pond production rather than feed, though isotopic lag may have masked late feed uptake. These findings demonstrate that optimized feeding strategies can enhance productivity while reducing feed inputs, thereby improving the sustainability of semi‐intensive Nile tilapia aquaculture in East Africa.