A general analysis is presented of long-term investigation on the composition, ecological characteristics, and state in common fishes, and a discussion carried out on the problem of how to propogate most valuable fishes in Taihu Lake. In Taihu Lake, 55 species were commonly collected during 1963-66, 1976-1978, 1981-1984 and 1988-1989. The composition of the fishes is characterized by proponderance in species and quantity of small and trashy fishes. In particular, the undesirable lake anchovy (Coilia ectenes) population is explosively developed with a yield accounting for 50-60% of the total catch of the lake. On the other hand, such natural populations black carp (Myiopharyngodon piceus), grass carp (Clenopkaryngodon idellus), silver carp (Hypophthalmichihys, molitrix) and bighcad carp (Aristichthys nobilis) almost disappeared, and the popula-tions of carp (Cyprinus carpio), crucian carp (Carassius aurataus) and bream (Parabramis Pekiensis and Megalobranta terminalis) etc. are greatly decreased by a yield lower than that in the 1950s. Based on the analysis, it is held that the synthetic effects include ecological characteristics of fishes and environmental factors, especially human interference. Therefore some proposals to solve the problem are put forward as follows: restricting the development of the lake anchovy, protecting some precious predatory fishes, as well as submerged plants, lake bottom or other spawning matrix in water, enhancing artificial stocking and strictly defining fishing scale of some valuable fishes.