I’ve become super attached to “holy carp”. It’s less vulgar than the obvious alternative, still gets the point across while being an amusing twist, and is potentially less blasphemous should one be concerned with such things.
At least, I assume so. Is it wrong to assert a carp might be holy? A priest could bless their water or something. I guess everything in that water could be considered holy after doing that. Holy sharks, holy sand, holy crabs...