About 2 months ago I purchased 7 Otto's of which 3 I placed in my 60 tank with a community made up primarily of T-Barbs and the other 4 Otto's I placed in my 120 community tank the only possible predators being medium size BPs and a 4" Pleco now donated to the LFS. I haven't seen the 4 Otto's in my 120 tank together for a long time sighting only 1 a week ago on the glass. I placed out some zucchini to bring them out but still no show. In my 60 tank they are always around and accounted for. Could the Pleco have taken the Otto's out as competition (no carcasses) before I got rid of him, or are Ott'o so slow that they were sucked up by the BP's which is so unlikely?