Molecular Biology Techniques 227 Using Molecular Biology Techniques to Characterize the Diversity of Amazonian Ornamental Fishes. Jorge I. R. Porto; José A. Alves Gomes, Izeni P. Farias* and Eliana Feldber Instituto Nacional de Pesquisas da Amazônia; *Universidade do Amazonas, Brazil. ABSTRACT This paper briefly reviews the genetic studies already performed in Amazon fishes and propose some methods that may be addressed to the study of genetic diversity of ornamental fishes in the region. From a suggested list of approximately 200 fish species to be traded in the aquarium industry in the Amazon, the cardinal tetra (Paracheirodon axelrodi) and discus (Symphysodon spp.) are among the most prized specimens. Despite the intense exploitation of these resources for several decades, basic biological and ecological parameters, including the genetic structure of the populations and their renewal capability, are poorly known. Up to the present, genetic studies in the Amazon included cytogenetics, isozyme electrophoresis, and DNA sequencing. The diploid/ haploid chromosome numbers have been determined for less than 20 ornamental fish species, isozymic studies were performed in about 5 species, and partial DNA sequences are available for less than 10 species. Most of these studies relate to fish evolution and biodiversity including phylogeny and of electric fishes (Gymnotiformes), catfish (Siluriformes), characins (Characiformes), and cichlids (Perciformes), and essentially no publication is available about population genetics or stock assessment. Therefore, as a continuum of Project Piaba, we propose that along with project Piaba 2000 chromosomal and molecular biology (microsattelites, PCR-RFLP, RAPD and DNA sequencing) should be used as molecular tools in order to characterize genetically the most relevant fish species being exploited in the Barcelos region. This will allow us to learn about their genetic diversity as well as the renewal capabilities of the stocks. RESUMO Este trabalho apresenta uma breve revisão dos estudos genéticos já realizados em peixes amazônicos e propõe alguns métodos genéticos que podem ser direcionados ao estudo da diversidade genética de peixes ornamentais desta região. De uma lista sugerida de aproximadamente 200 espécies de peixes ornamentais para serem