For the sake of controlling algal bloom caused by the eutrophication of water bodies, the orthodox biomanipulation approach advocates the stocking of piscivorous fishes to suppress the planktivorous fish so as to bolster the zooplankton population, which is entrusted to suppress the algal community through its grazing pressure.. According to this line of thinking, the planktivorous silver carp (Hypophthalmichchys molitrix) and bighead carp (Aristichthys nobilis) should be the target of elimination from the water bodies concerned. Authors of the present paper, however, consider that the most undesirable water bloom in Chinese lakes is the cyanophycean or cyanobacterial Microcystis bloom, which can hardly be consumed by zooplankton, accordingly, it seems more reasonable to employ the silver carp and bighead carp directly for the control of Microcystis bloom. Thus, during the years 1989 to 1992, three in situ enclosure experiments were undertaken in Lake Donghu of Wuhan city, and the experiment was further repeated in 2000. The results of all these experiments corroborated that Microcystis bloom, vanished from Lake Donghu for 18 years already, did resume in the enclosures devoid of fish. In those enclosures stocked with adequate densities of silver carp or/and bighead carp, Microcystis bloom failed to occur. In those fish-less enclosures where Microcystis bloom already occurred, the introduction of silver carp or/and bighead carp at an adequate density did wipe out the bloom within a short period of time; whereas the stocking of grass carp (Ctenopharyngodon idellus) in these enclosures brought no effect at all-the bloom persisted throughout the experiment. The above results demonstrated consistently that the planktivorous silver carp and bighead carp could reliably suppress Microcystis bloom; the effective stocking rate or biomass of these fish for the elimination of Mycrocystis bloom has been estimated at 46~50 g per cubic meter of water. The biomass of these two fishes in Lake Donghu was not up to this standard until the year of 1985, hence the exceptional absence of this bloom from the lake that year. In the succeeding years, the fish yield of the lake has been on the rise year after year, implying a steady increase of the biomass of these fishes in the lake, hence there has been no opportunity for the Microcytis bloom to recur. Evidently, water quality and other non-biological environmental factors of the lake are still vulnerable to the formation and development of this bloom, and if the annual fish crop declines to below the threshold level (i.e., the 1015 t fish yield of the lake in 1985), the recurrence of Mycrocystis bloom will be inevitable. The doctrine and practice of the orthodox approach of biomanipulation could in no way check the outburst of this bloom; on the contrary, the direct suppression of this bloom through the phytoplanktivorous fishes silver carp and bighead carp has its experimental grounds and has been proved effective in the fishery practice of Lake Donghu.