Aquaponics System Optimization: Evaluating Fish-to-Plant Ratios on Water Quality and Yield of Lactuca sativa

Advances in Agriculture and Agricultural Sciences | Vol. 12, No. 4, April 2026 | pp. 72–77

DOI: 10.46882/2026.AAAS.120402

Research Article

Title: Aquaponics System Optimization: Evaluating Fish-to-Plant Ratios on Water Quality and Yield of Lactuca sativa

Names of Authors: Nielsen, K. B.¹, Hansen, T. M.¹, and Sorensen, J. L.²

Authors’ Affiliations: ¹Department of Environmental Technology, Technological Institute of Denmark, Aarhus, Denmark. ²Department of Bioscience, Aarhus University, Silkeborg, Denmark.

Abstract: Recirculating aquaponic loops present viable alternatives for urban food systems by co-culturing Nile tilapia (Oreochromis niloticus) alongside lettuce (Lactuca sativa). Balancing nutrient generation with vegetative uptake remains critical to prevent phytotoxicity or system imbalances. This experiment tested three distinct fish-to-plant biomass feeding ratios (fifteen, thirty, and forty-five grams of fish feed/square meter of plant space/day) inside a deep-water-culture configuration over a 60-day tracking period. Total ammonia-nitrogen, nitrite, and nitrate levels were logged every 48 hours. The 30 g/m²/day ratio achieved optimal nutrient homeostasis, keeping toxic un-ionized ammonia concentrations below 0.05 mg/L while providing sufficient nitrate accumulation (64.2 mg/L) for leafy growth. Under this layout, lettuce head biomass averaged 245 ± 12 g, showing no symptoms of iron or magnesium deficiencies. Crop growth index parameters matched or outperformed conventional hydroponic control treatments. Increasing inputs to 45 g/m²/day caused sharp accumulations of organic solids, overloading biofilter capacities and lowering dissolved oxygen profiles below safe thresholds.

Keywords: Recirculating aquaculture; Hydroponics; Nitrogen conversion; Biomass balance; Tilapia farming; Leafy green production.

Manuscript Timeline: Received December 10, 2025; Revised February 12, 2026; Accepted March 15, 2026; Published April 22, 2026.

Citation: Nielsen, K. B., Hansen, T. M., and Sorensen, J. L. (2026). Aquaponics System Optimization: Evaluating Fish-to-Plant Ratios on Water Quality and Yield of Lactuca sativa. Advances in Agriculture and Agricultural Sciences, 12(4), pp. 72–77.

Subscribe to read the full article: https://internationalscholarsjournals.org/subscribe-to-read