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Abstract
There are numerous water bodies in South Africa that have the potential to be utilised for
aquaculture practices without an additional load being placed on water consumption. For
example, the Western Cape has over 2 000 irrigation dams each with a water volume in
excess of 500 000 m3 which are suitable for aquacultural activities and have the potential to
produce an estimated 5 800t of freshwater fish per annum. The question that arises is
whether the fish enrich or pollute the water relative to the primary function of that water, e.g.
irrigation of high value crops such as table grapes and deciduous fruits destined for export.
One of the major chemical compounds derived from an aquaculture industry causes an
increase in the nitrogen content of the water, which is caused by both excess feed
decomposition and fish metabolism. An intensive investigation of an integrated agricultureaquaculture
project in the Western Cape showed no negative impact of the aquaculture
activity on the water quality in terms of nitrogen, pH, turbidity, conductivity or total
dissolved and suspended solids content. The aquaculture project delivered 4 500 kg of trout
over a seven month growth period in a cage system which realised a return of 17.2% on the
investment.