In this research it was evaluated the effect of background color on the development of the chromatophores in Macrobrachium tenellum prawns, six juvenile prawns were exposed to five background colors: black, white, pink, red, white and green; each one in triplicate, for 60 days. The development of the chromatophores was evaluated by means of the chromatophores index using a scale of 1 (the maximum concentrated pigment) to 5 (the maximum dispersed pigment). The coloration was analyzed in four anatomical regions of the organisms with the HSB model (hue-saturation-brilliance). The results show that the prawns modify their pigmentation according to the different background colors of experimental aquariums.