Goldfish disappearing!

Question
We have a raised garden pond, set up four years ago.We have successfully kept a mixture of goldfish and shubunkins.  These all reappeared after the winter and started to feed and be seen around the pond as usual.  Then they suddenly disappeared down to the bottom of the pond about a month ago and have stayed there ever since!  Occasionally we see them lurking in the gloom but they will not come up for food so I have stopped offering it.  I introduced three new shubunkins and these promptly disappeared to the bottome as well!  Water quality is fine, weather is warm.  ny advice gratefuly received.

Answer
Hello Cathi-

I don't know much about ponds, but are there any raccoons/cats/herons in the area that may be trying to "fish out" your fish? They may be hiding out of fear, or the water temperature at the bottom may be cooler and more to their liking during the hot summer days.

Hope this is helpful, sorry I can't offer more!
-Amber Worman