Comparison of Leafy Vegetable Growth in Coupled and Decoupled Aquaponic Systems Using Cold-Water Rainbow Trout (Oncorhynchus mykiss)

This field-demonstration study compared the growth performance of five leafy lettuce cultivars grown in coupled aquaponic systems (CAS) and decoupled aquaponic systems (DAS) using cold-water rainbow trout (Oncorhynchus mykiss). Due to the practical constraints of full-scale field facilities, tank-level replication could not be established, presenting a statistical limitation (pseudoreplication) for inferential hypothesis testing. Therefore, growth parameters were evaluated descriptively based on repeated measurements over a 3-week harvest period (weeks 18 to 20). Across all evaluated cultivars, DAS showed a consistent descriptive trend of higher leaf biomass production compared to CAS. Integrated descriptive analysis across all cultivars further demonstrated that DAS maintained higher median and overall biomass distribution ranges than CAS. Higher nutrient accumulation (nitrate and phosphate) in the DAS plant zone contributed to enhanced crop growth. Although the lack of facility-level replication remains a methodological limitation, these field-scale findings suggest that DAS offers a more effective nutrient management strategy than CAS for maximizing leafy vegetable productivity in trout-based aquaponics.