where the $%^# do fish disappear to?

ok, I have been adding a few more fish to my pond this year.
I am 'trying' black moors & orandas etc. plus a few small koi .

most of them had just vanished.
I 'did' find a dead fish on the bottom of my pond. by sheer luck, as the
light was in the riight spot.

questions: I thought dead fish floated? (most of my other dead ones did),,
so much easier to find. I figure they just died........ somewhere......
I 'did' see a cat by the pond the other day. but I cannot figure out HOW it
would get any of the fish, unless it jumped in....... unless it fished out
the dead ones floating by the side?
I have plenty of fish, & no one is spastic, as if a heron or raccoon showed
up. pretty much all of my last years fish I can account for, its just the
newer ones this year.
the small koi (about 3-4 inches) swim pretty darn fast.... cannot see how
anything could catch them!

now, I do NOT have ginclear water, although if the angle is right I can see
to the bottom, but cannot make out anything in the center of the pond where
it is deeper. so they could be dead there......... I cannot imagine they do
not come out to play with the other fishes,, when the mob is eating,
practically everyone is there! (do SOME fish just hide & never come out?)

I do have another question,, maybe the spawning is getting to them??? even
though the goldfish ARE small the bigger fish are including them in all the
chasing around the pond, when I found a smaller oranda dead I figure he MUST
have just gotten exhausted from the chasing! If that is what is happening,,
where the heck are the corpses?
there are plenty of plant pots for them to 'hide' in, but seems like the
spawners just run railroad over everything!
(btw,,,,,,,,,, other question,, both koi & goldfishes are involved all at
once,,,,,,, is this normal? chasing each others species?)

what ticks me off the most is I bought a 5" black moor for $24. & its
gone...... *pout* ( just dang it,,,,,,,,, if I could find it dead at least
I could take it back for refund at LFS)

but the smaller koi are what has me scratching my head,, too swift to be
caught & they arent caught on the filter intake.
where do they go????
I WISH I took pictures of them when I bought them, than I could be sure of
what I have!