I think if they were still there, they'd be 12" or more WITHOUT having had any supplemental feeding, bigger having been fed. It seems very unlikely that you would have no sightings at all.

Unfortunately, this makes it seem likely they are gone. Could 50+ CC die and leave no trace - yeah, under some circumstances I think they could (Winterkill under ice for one). I'm assuming you have regular (daily?) visual access to the pond - if not, raccoons etc. could have cleaned them up pretty quickly (I've never seen a dead fish at my pond that looked like it had been there more than 24 hours). Doubtful even persistant fishing (by poachers, otters, herons, or space aliens - water turkeys I would say were possible if we had them here) could get them all.

Can you think of any situations where they might have died? They might have been the most susceptible to low O2 problems if they were the biggest fish in the pond. Any chemical applications in the pond or watershed that might have affected them?

"Live like you'll die tomorrow, but manage your grass like you'll live forever."
-S. M. Stirling
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