Grandpa never swore, at least not in any way that I could understand to be swearing. My dad, in contrast, would occasionally burst out with an Italian-sounding phrase and then chuckle at his attempt at conveying an air of sophistication. Despite my suspicion that he was making something up, I remember thinking, “Wow, my dad can swear in Italian.” For all I know today, he could have been saying something like, “Satan sucks sour sassafras.” But at the time, I could recognize some of the sounds as “bad words.”
But Grandpa didn’t swear, though I remember a strange little phrase he would occasionally use to emphasize a point he was making: “By the gods and little fishes, the deer I shot was a big one.” That was a confusing one, but since Grandpa said it and Grandma never corrected or reprimanded him for saying it in front of us kids, I assumed it was OK to say, like on the order of, “Gee willikers, the deer I shot was a big one.”
But he used the word “gods,” which threw me off. Being raised in the Roman Catholic church, I learned that there is only one God; theologians call that monotheism. In fact, the Bible teaches that there is one and only one God, the Creator of the universe. Grandpa didn’t believe in multiple gods, did he? No, he didn’t—but it seemed like he was calling on “gods” to bear witness to the truth of his statement: “the deer I shot was a big one.”
So, where did he get that from, and what did it mean? A little research helps answer the question. It turns out that Gramps modified a phrase that came into being in the 1800s, “Ye gods and little fishes.” That phrase was a more elaborate version of “Ye gods,” which originated in the 1700s. The Free Dictionary gives this description of the phrase: “Euphemism, old-fashioned. An exclamation of shock, astonishment, or incredulity. A more emphatic, though less serious, way of saying, ‘ye gods,’ a minced oath used as a stand in for the more blasphemous ‘Oh my God!’ Primarily heard in the US.” Where and when did the childish “and the fishes” get added? Possibly that addendum may have further diluted the original to a more secular, less offensive saying. A variation of the phrase has survived more recently, “Egads, the deer I shot was a big one.”
So did my revered grandfather swear? I don’t think so, and no one else seemed to think so either. He was always respectful toward God. He may have held a grudge from his boyhood against a priest who hit him over the head with a Bible during a church service—he quit being an altar boy after that incident—but he never questioned God. He was a man of faith who honored God. He reminds me of the Roman centurion in the Bible who is described as a “God-fearer” (Acts 10:1-2). He respected God and was a good man.

Mom, born in 1912 and a solid Episcopalian used this expressions routinely. I got it! Nice review/explanation above.
Tom, I just saw your comment. Your sharing that brought a smile to my face.