Argulus japonicus in the Olifants River system - Possible conservation threat?

Argulus japonicus, an introduced fish parasite, is reported from fishes in the Witbank Dam and at the Olifants River Lodge in the Olifants River system. All fishes collected from Witbank Dam were infested and the maximum number per fish was 87. No parasites were present on fishes from the Lowveld region. This parasite was reported from the Vaal River where epidemic numbers occur. It is suggested that water transfer from the Grootdraai Dam in the Vaal River brought about the infestation in the Olifants River. The spread of the parasite downstream is probably prevented by low water temperature regimes on the Highveld. Should a flood occur, fishes and parasites could be washed downstream to the Kruger National Park where favourable water temperatures could lead to massive infestations and resultant fish kills.