Allright, which one of you ate my cuber?

I left 2 thick slices of cuber in my tank last night to collect snails. I managed to collect 2. When I picked the cubers up, there were huge holes all over the cuber. I have a molly, guppies, neon tetra, and swordtail. Oh, and 2 new otos. Could they be the culprit? I'm just very curious, because I might give my fishes cuber once every week or so, and is it bad?