“…Many enzymes, such as esterases, show pronounced differentiation in isoenzymatic patterns in many organisms, including plants (Anti, 2000), phytonematoids (Alonso and Alfenas, 1998), mollusks (Richardson et al, 1982) and fish (Payne et al, 1972;Reinitz, 1977;Solomon and Child, 1978;Ferguson, 1980). Although Serrasalmus is one of the most widespread and specious South American piranha genera (Machado Allison and Fink, 1995) only a few allozyme genetic studies have been carried out on this piscine group since the study of Serrasalmus spilopleura lactate dehydrogenase (LDH), malate dehydrogenase (MDH) and glucose phosphate isomerase (GPI) isoenzyme patterns by Cestari (1996) on fish from the Paraná and Paraguai river basins.…”