Although most of the existent information regarding the sensitivity of fish to pollutants has aimed to the study of Holartic species (Ramamoorthy and Baddaloo 1995), contributions on organisms from other types of ecological communities belonging to Neotropical environments have been recently undertaken considering native and introduced species (Domitrovic 1997; de la Torre et al 2000 a, 2000 b; Ronco et al 2000, Carriquiriborde and Ronco 2002). The present study reports data on the acute toxicity to five metals of the widely distributed species Cichlasoma facetum in the South Eastern Neotropical region of South America (Ringuelet et al 1967). This species is found in a wide range of habitats, but it is more abundant in ponds, small lakes and streams, with an approximate interval of 30 °C temperature tolerance. Like most other Cichlids, it can be easily kept and reproduced under controlled laboratory conditions. The species spawns every 20 days under favorable conditions, producing between 600 to 1,800 (2 mm of diameter) brown eggs. These characteristics make the species a suitable organism for laboratory toxicity testing.