The culture of fish floating net cages is one of the main activities of fisheries in Maninjau Lake. Recent developments indicate that the various activities has caused various problems, such as the decline in lake water quality. The decrease in water quality has caused mass mortality of fish that are kept in floating net cages, for that the observation of water quality conditions especially tracemetals were done. The results showed Cd 1.11- 32.65 μg/L, Cu 109.5-451.50 μg/L, Pb 0.16-27.66 μg/L, and Zn 82.50 - 409.01μg/L. With reference to the quality standards of water quality according to Government Regulation Number 82 in 2001, it can be concluded water quality has not been entirely feasible for fish farming. These conditions will deteriorate further in the event that the timing of the upwelling process can not be predicted.