Well darn. A week ago I brought home 4 little otto cats and put them in my 90 to help with the diatom. They were really going to town then all of a sudden seemed to stop. Today, I found 2 dead ottos stuck on the intake tube of my Aquean 55/75 HOB - so I guess I know why they stopped working.
I think I saw 1 alive today. Have no idea about the other since I've barely seen them since I got them, I've never known what was going on.

Is it possible the intake tube sucked them up against it while they were cleaning and trapped them and that's what killed them?
Or is it more likely a congo or one of my other fish killed them (see sig line) and I should have known it would happen?

Water perims are 0/0/<5. PH 7.2

Ideas?
Thanks