In spite of the recognized rusticity of the cachama, the increasing tendency towards the intensification of the production systems of the species, begins to favor the increase of sanitary problems, which will have to be characterized in order to be able to establish methods of diagnosis and rational plans of prevention. Since the knowledge of ictiopathology of native species is incipient, among other things because of the little availability of information on basic aspects of histology, embryology, physiology, anatomopathology, immunology and epidemiology,  the establishment of investigation projects that allow to know such aspects in order to support the production of these species technically becomes necessary. With this work begins the acquisition of knowledge about the basic immunologic aspects of the White Cachama (Piaractus brachypomus).For this end, gamma-globulins were purified by means of the elution starting from agarosa gels. The presence of two possible attachés of IgM was confirmed. One of them seems to correspond to form monomerics and the dependability of this purification method allows us to obtain small quantities of protein without the presence of pollutants. The reactivity of the obtained antiserum only reacted against the fraction of the gamma-globulins, what was proven by means of the inmunoelectroforesis technique with the serums of White Cachama. Also, they obtained two bands with SDS - PAGE under conditions without reduction; the first one with an approximate weight of 80 kDa and the second one about 70 kDa. Under reduced conditions, two bands were obtained, the first one with an approximate weight of 90 kDa and the second of 70 kDa.