This chapter describes the possibility to combine wastewater treatment in recirculating aquaculture systems
(RAS) with the production of crop plants biomass. In an aquaponic RAS established in Waedenswil, Zurich,
the potential of three crop plants was assessed to recycle nutrients from fish wastewater. A special design of trickling
filters was used to provide nitrification of fish wastewater: Light-expanded clay aggregate (LECA) was filled
in a layer of 30 cm in vegetable boxes, providing both surface for biofilm growth and cultivation area for crop
plants. Aubergine, tomato and cucumber cultures were established in the LECA filter and nutrient removal
rates calculated during 42–105 days. The highest nutrient removal rates by fruit harvest were achieved during
tomato culture: over a period of >3 months, fruit production removed 0.52,