Protein and mitochondrial DNA have been used as molecular markers to assess variability in stock identification studies of fishes. Protein and mtDNA used for electrophoretic analysis are extracted from tissues, which often leads to death of the individuals. In this study, we present a skeletal muscle biopsy procedure to extract mitochondrial DNA that does not require specimen sacrifice. Eighty pirapitinga-do-sul (Brycon opalinus) were biopsied by the present technique, with no mortalities recorded. Total DNA was extracted from muscle and digested by restriction enzymes ApaI and HpaI. The mtDNA fragment patterns were hybridized with 32P-labeled pirapitinga-do-sul mtDNA probes. The described technique is simple and may be useful in protocols requiring tissue extraction for DNA and protein analyses without loss of the individual investigated.
