Revolving Algal Biofilm (RAB) reactors offer a space-efficient and low-energy method for producing algal biomass by cultivating algae on a rotating belt surface. Their unique biofilm-based growth mode simplifies harvesting and enhances nutrient recovery by maintaining continuous contact with nutrient-rich water. Despite these advantages, the application of RAB systems in aquaponic configurations has received limited attention, especially in relation to system performance, nutrient recycling, and algal quality. This study investigated the integration of Chlorella vulgaris cultivation using a RAB system within a coupled aquaponics configuration, compared alongside a decoupled setup and a conventional fish–plant control. Over a 35-day period, nine independent systems were monitored to evaluate fish growth, lettuce yield and algal biomass productivity and nutritional composition. Fish growth, survival and lettuce yield did not differ significantly across treatments demonstrating that algal integration, whether coupled or decoupled, did not compromise primary aquaponic outputs. Although the decoupled system produced more total algal biomass, the coupled RAB system demonstrated higher biomass productivity when normalized by culture surface area. In terms of nutritional composition, RAB-derived biomass exhibited higher crude protein and lipid than decoupled biomass, along with enriched essential and non-essential amino acids (e.g., lysine and methionine) and greater proportions of long-chain PUFAs (e.g., ARA, EPA, DHA). Overall, the coupled RAB system enhanced biomass productivity per unit surface area and biomass nutritional quality without negatively impacting fish growth or plant yield. RAB-coupled aquaponics thus offers a practical route to produce high-value algal biomass while maintaining system performance, supporting circular nutrient recovery and diversified outputs.