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Limited information exists on microbial contribution or environmental processes that underlay effective aerobic mineralization of fish effluent; however, studies suggest that nutrient recovery from fish solids can be significant (Cerozi and Fitzsimmons 2017, Cerozi and Fitzsimmons 2016, Goddek et al. 2018, Rakocy et al. 2016, Tyson et al. 2011, Yogev et al. 2016, Khiari et al. 2019, Graber and Junge 2009). Preliminary results from on-site AP research systems at Kentucky State University (KSU) show that aerobic mineralization of fish effluent for 14 days resulted in a 143% increase (7.61 to 18.5 mg/L) in phosphate (PO₄), a 47% increase in nitrate (NO₃⁻-N; 28.5 to 41.7 mg/L), and ≥ 20% increase in Ca (57.97 to 74.23 mg/L) and K (27.38 to 32.7 mg/L) compared to system water (unpublished). However, even if nutrients are recovered from effluent and provided in the right form and quantity, interactions with other nutrients and water chemistry can sometimes make them unavailable to plants (Bryson and Mills 2014).

Direct application: Waste can also be applied directly as a soil amendment, composted through traditional heat-treatment methods, or via vermicompost (worm composting). Direct application should be used as a low-grade fertilizer or if the slurry is less than one percent solids. Heat-based composting of dewatered fish solids requires additional expertise and labor cost but can add an important additional income stream. Vermicomposting uses similar methods to traditional composting but does not rely on heat to process waste. Worms consume organic matter, fragment and aerate the solid material, and can potentially provide a supplemental live feed for fish (Yeo and Binkowski 2010). Compost can include vegetable waste or other compostable materials from production. It is not uncommon for mineralized effluent to be bottled and sold directly to home gardeners or small greenhouse operations; however, some restrictions may apply depending on your local regulations.