I have had 3 mysterious disappearances from my 10 gallon tank - 2 were mollies (black) and one recently was a buenes aires tetra. they completely dissappeared, and trust me, I have looked everywhere. could it have been my Pleco? he is about 7 inches (I know, too big for a ten gallon, he's moving into a 55 as soon as its cycled). my roommate is convinced that Bob (Pleco) is the culprit. is it possible?