The brandtii i currently have is nearing the 10 inch mark and is completely gold. I have fallen inlove with piranhas, brandtii and irritans beeing my favorite. its more of an infactuation really. i have also heard amongst the piranha boards that the smaller silver brandtiis are most likely female and the males will get larger and completly gold in color.. i know many piranha enthusiasts have said that there are no ways to tell serrasalmus species apart and most color differences are fish collected from different locales. Seeing that the brandtii is only seen and collected from the Rio Sao Francisco, i find it hard to believe that color would vary amongst individuals living in one body of water. Even if proven to be wrong ,then i would still like to own another brandtii to see if there is any difference in aggression levels and feeding strategies between the two color morphs.