Mine was when I was 18 and caught my first Tiger Musky. At the time I didn't know they were in the Potomac River and caught it fishing for other fish. Had the fish officially weighed not even positive of the species only going off the MD DNR book they gave me when I purchased my license. I was 2 ounces short at the time with the record of 17-4. This record has been broken several times since then and my personal best Tiger is 25-6 currently.
The only other fish that is questionable is my brother caught a Crappie once on a hellgrammite that measured a little over 22.5" fishing for bass. Since I don't fish for them or know anything about then when he caught it just seemed like a big one. We just threw it back in after measuring it and forgot about it. Then when we stopped by a local tackle shop that kept pictures of the biggest fish customers caught for prizes, I noticed the biggest crappie was 17". Not sure how his fish would have stacked up but it is the biggest Crappie I have every seen besides the world record one at BPS in Missouri.
Allen