The study of metal accumulation in fish represents one of the most actual directions of ecology, being a component of the ecological status of water ecosystems monitoring. Due to the fact that trace metals may have a negative impact on the environment a number of metals are included in the list of main pollutants, with an established allowable concentration limit. The investigation of metal accumulation in fish at the moment is developed in several directions: 1) revealing of the accumulative capacity of fish and establishment of the main factors, which determine the accumulation of chemical elements in fish; 2) quantification of the metal influence on fish growth and development during ontogenesis; 3) investigation of metal accumulation in fish, as well in nutritional product. The investigations mentioned above are actual, especially for the Republic of Moldova, where rivers and water accumulation reservoirs are subject to negative human activity, resulting in a continuing diminution of the number and biomass of valuable fish species. The current study is focused on the influence of metals on developmentand gametogenesis in breeding fish. The period of early ontogenesis is the most vulnerable period in fish development.Mature fish posses a rather developed mechanism that regulates the processes of accumulation and redistribution of microelements between different organs, depending on the plastic and generative metabolism of fish. The laws of the metals accumulation dynamics in organs and tissues of fish from different aquatic ecosystems on the diverse ontogenetic phases, and the dependence on the process of environmental conditions served for the elaboration of theoretical bases on resistance and level of tolerance in ichthyofauna and will significantly contribute to elucidation of some aspects of the fundamental and practical character in regard to aquatic ecosystems, assessment of the ecological situation, environmental protection and rational utilization of biological resources. Acknowledgement: The study was performed within the projects:15.817.02.27A-AQUASYS, 18.51.07.08A/PS,BSB 165 HYDROECONEX, BSB 027 MONITOX, DANUBIUS-RI, MIS ETC 1676, MIS ETC 1150.