Catsmom, It has happened to many fish it seems. I have had it happen in my pond, where a particular fish was missing for over two months and suddenly reappeared one day.
Many other pond owners on this forum, have reported the same weird story about an errant fish returning, none for the worse, to their ponds, after an absence of a few days or weeks.

Some years ago it was decide by a few of us here on this forum, after reading about so many of these "Missing Fish Reports" and giving it serious consideration, that it must be the aliens who are abducting these fish, doing what they do to fish and then returning them back to our ponds.

We we figured the alien abduction theory, explained it more logically, than the fish being stuck behind a rock, in a bottom drain or in between the skimmer and the liner for days/weeks at a time scenarios.
People find stories like that very hard to accept.
Your friends will give you strange looks and will avoid having conversations with you!

So just put it down to an alien abduction and call your local television news room right away! LOL
"Horton"

Twice we got a new fish and after placing them in the pond, they disappeared. The first came out after 3 months. The second came out after 2 weeks. Our tadpoles never showed up again. We tried twice. We give up on having frogs.

I have the opposite problem: I have a tiny pond next to my small pond that I only keep plants in. Two years running now I have fish in the pond where I've put no fish.

This year they are of some unknown species. I didn't have any of those fish (but now I do).

Wow, ernie, that's strange. Could someone have sneaked them in? Maybe fish eggs in a plant? Hmmm....