Question
Dear Robyn,
I have an outdoor pond that seven comet goldfish (about 2-3 inches in length) have lived in since I put the pond in the ground.  They have survived two winters and thawed out each spring.  They would come to the edge and beg for food like pets.  I noticed this spring I have many frogs living among the grasses and plants around the edge of the pond.  At any given time there are four to five frogs in the pond every day.  I now only have three goldfish that come up for feeding.  I have seen no dead fish.  Could frogs kill and eat goldfish?

Answer
How big are the frogs?  If they're bullfrogs that are larger than the fish, then they could eat the fish.  Other species are less apt to eat fish.  It would help to identify the frog species.  

Other predators (of which there are many) could have also gotten the fish if they are truly gone.  How big is the pond?  At 3+ years old, I would expect goldfish to be more like 5 inches and not just a few inches so I'm guessing it's a small pond.  Small ponds make it easier for predators to get the fish.  

The fish did not thaw out as goldfish cannot freeze solid and survive upon thawing.  I'm sure you meant that the pond thawed.  For information on overwintering, see http://www.fishpondinfo.com/winter.htm
My frog page is at http://www.fishpondinfo.com/frog.htm
Good luck!
Robyn