If it raided your pond it was likely a Great Blue Heron. The tricolor prefers crabs, if it can get them.
Ah, you’re probably right. We do have Great Blues around here.
It’s amazing how they can spot a backyard pond in the middle of suburbia and know there might be lunch there. We lost our fish while the herons were in nesting season, so I’m sure they were searching far and wide for food for their young.