SUMMARY
Specific antisera to Oxydoras niger (Doradidae: cuiú-cuiú) and Plecostomus plecostomus (Loricariidae: cascudo-pedra) hemoglobin were tested against fish hemoglobin of Doradidae; Auchenipteridae; Pimelodidae; Angeneiosidae; Loricariidae and Callichthyidae.
Serological double diffusion tests in agar have shown that O. niger antiserum gives positive reaction against hemoglobin of all the species of "bagres" and "cascudos" tested with only two exceptions P. plecostomus (cascudo-pedra) and P. pardalis (cascudo comum) fraction I hemoglobin which gave negative reactions.
On the other hand, the P. plecostomus antiserum gave positive reaction only for the homologous and P. pardalis fraction I antigens.