losing fish in pond

[cemantic]

After having our goldfish spawn in our pond ( http://ovas.ca/index.php?topic=29231.0 )  we seem to have lost another fish.  This one was probably the mom of the spawned fish.  She tended to settle in an area close to the surface unfortunately she has gone missing.

We had eight goldfish from last year.  One disappeared without a trace within the first two weeks of putting them back in the pond in the spring.  Now this second one about a month later.  No ripped up plants or other signs of what may have happened.

Not sure what to do to protect them.  One of those water motion detector sprayers may be a solution but we have cats, which is another possibility but no evidence that it was them and they are in at night.

I would prefer not to put a cage around the pond, which sort of defeats the purpose of having one to begin with.

Thought of a bright light on a motion sensor.

Anyone with any experience in this?

Suggestions?

[bergenm]

You could alway turn the sensor on in the evening and off in the morning.

If there are no other signs, you might have a heron or kingfisher visiting your pond, snakes and bullfrogs would be other possibilities...