The objective of this investigation was to evaluate fish abundance and community composition upstream and downstream of the Huntly Power Station discharge by boat electrofishing in order to contribute to effects assessment of the thermal discharge. This limited sampling suggests that koi carp had the greatest biomass of any fish species, and were aggregated immediately downstream of the Huntly Power Station. Previous work would suggest that a single electrofishing pass catches about half of the fish present. The method is known to under-sample eels and catfish, but is a robust semiquantitative tool to estimate relative fish abundance.