ineffective (pers. obs.). Sampling of fishes specialized for life in this dark environment therefore requires dedicated effort and specialized equipment. Major expeditions with the deep water ichthyofauna of main Neotropical river channels as their focus have been undertaken at least twice to the Orinoco River, and four times to the Amazon River. In 1978 and 1979 the Duke University research vessel Eastward trawled the lower channel of the Orinoco (Mago-Leccia et al., 1985) and in three expeditions during the low water seasons of 19921994 and one during the high water season of 1996, the Calhamazon Project sampled main river channels of the Bra.zilian Amazon (Cox Fernandes