Abstract: Two kinds of taphonomical facies are recognized in the type section of No. 2 quarry of the Miocene Shanwang Formation, Shandong, east China. One is tile thinly bedded diatom-bearing mudstones and shales typical of the upper part of the section. The fact that the fishes are not perfectly preserved is interpreted as fish decaying in a hypolimnion wanner than about 15℃ and lake depths less than 8-12m, and areobic conditions suitable for scavengers. The other taphonomical facies is the thinly laminated diatom shales typical of the lower part of the section, which are composed of couplets of the light-coloured diatom-rich laminae and dark grey or dark brown organic-rich laminae. The fishes show no examples of scattering, disarticulation or macroscopic scavenger disturbance, indicating a low energy environment, lake depths more than 8-12m, and anoxic or anaerobic conditions and temperature lower than 15℃ in the hypolimnion. The main cause of fish death is suggested to be overturn-induced anoxia in a monomictic lake.