Ionizer wrote:

This afternoon, just half an hour ago, I came home to find another otto
cat jammed into the intake slots of our filter tube, hanging
motionlessly. Over the months, this is where I've found most of our
small handful of fish losses- I assume that they drift lifelessly and
end up being pulled gradualy towards the tube.

You don't say what filter you have, but I have an Aquaclear filter with
a conical dip tube intake with rather wide intake slots. To keep large
chunks & snails out, I've cut a hole in a small Aquaclear sponge filter
and put it over the intake tube. This keeps live things from being
sucked into the tube. (Previously the filter was sucking snails out of
their shells, but now my shrimp can land and take off from the sponge
with no problems.)