Integrated multi-trophic aquaculture (IMTA) provides the byproducts, including waste, from one aquatic species as inputs (fertilizers, food) for another. Farmers combine fed aquaculture (e.g., fish, shrimp) with inorganic extractive (e.g., seaweed) and organic extractive (e.g., shellfish) aquaculture to create balanced systems for environment remediation (biomitigation), economic stability (improved output, lower cost, product diversification and risk reduction) and social acceptability (better management practices). https://en.m.wikipedia.org/wiki/Integrated_multi-trophic_aquaculture

Under IMTA production, the uneaten feed and wastes of one species are recaptured and converted into feed, fertilizers, and energy to another species. IMTA can promote aquaculture sustainability, with environmental, economic, and social advantages. https://www.frontiersin.org/articles/10.3389/fmars.2020.00156/full

Renewable energy use is aquaponics interests me.