Preliminary study on element mass fraction determination on catfish samples from Paraguay

South American catfish (Pseudoplatystoma), commonly known in Spanish as atigrado or surubi and in Portuguese as surubim or pintado is a large fish that typically reaches 1 m long and weighs 60 kg to 80 kg and may be found at the basins of the Amazon, the Sao Francisco and de la Plata rivers, usually in riverbeds and deep wells. Being a much appreciated fish for human consumption, it is quite sought after by fishermen who have been contributing to the reduction of the stocks. This fact attracted the attention of the Paraguayan authorities to the point of imposing restrictions to free fishing and commercialization. This study aims to assist the conservation efforts towards this fish by investigating its exposure to possible pollutants. Preliminary results on element determination on six samples of catfish from Paraguayan rivers are presented. Cs, Co, Fe, Se and Zn were determined by applying an Instrumental Neutron Activation Analysis method. While these element levels were lower than the legislation for human consumption, the elements As, Cr e La were not detected in the samples as they are below the detection limit of the method employed. Atomic Absorption Spectrometry was used to investigate the presence of Cd, Hg and Pb in the samples. Hg was detected in the samples while Cd and Pb were below the detection limit of the method. (author)