ing. Ep Eding

Area of interest
Ep studies water quality management in Recirculating Aquaculture Systems (RAS). The main focus is
on understanding how feed composition and water treatment affect water quality, fish performance
and waste discharge from RAS.

Relevant research
Fresh water fish cultured in recirculating aquaculture systems (RAS) with a low water refreshment rate
can be exposed to relatively high water mineral concentrations. Little information is available if water
born minerals in freshwater partially cover the mineral requirements of fish. Therefore, research was
started to assess if water born phosphorus can partially cover the phosphorus requirement of fish. The
impact of phosphorous concentration in relation to dietary phosphorous content, phosphorous balance,
performance and energy balances in Nile tilapia was studied.
Besides minerals also steroids accumulate in low water exchange RAS. Limited information is available
if steroids accumulate to concentrations in RAS effecting fish performance. Therefore, research is done
to determine the concentrations of three steroids in commercial RAS, if these concentrations can be
sensed by fish and if they affect fish performance. Finally we want to determine the factors which

determine steroid concentrations in order to control water quality (steroid concentration) in RAS.

Contact info
Wageningen University, Aquaculture and Fisheries Group (AFI)
De Elst 1, 6708 WD Wageningen, The Netherlands