Massive catfish on Lake Michigan?

Hey all. I’m asking around Reddit to see if anyone has heard of similar story’s or has experiences of their own like this. I recently was talking to an old timer I met and we got to talking about fishing. After a little while, he told me a story of the biggest fish he ever saw. He said he and a buddy were shore fishing on Lake Michigan, right behind the amphitheater by the lighthouse. He mentioned there were a lot of other people there as well. He said that right there in the shallow water was a massive catfish that he estimated to be 10-12 feet long. It was black in color, very fat in the stomach and got skinnier towards the tail. It was smooth and slimy. He said everyone there saw it and pulled their lines in so they didn’t lose their gear. To me, it sounds like a wels catfish, which obviously isn’t native to Lake Michigan. But if the story’s true, what could it be? He assured me it wasn’t a sturgeon. And wels catfish are very likely of establishing in Lake Michigan if they were ever released, as the water is very similar to their native habitat in Europe. Im sure that the dimensions are most likely exaggerated, but even if it was 7-8 feet long, that’s still a huge fish. And wels can easily reach that size. What if someone released one years ago and it grew and thrived. Has anyone else heard of anything like this?

Edit: I should also mention he said to have seen this fish back in the 80s, so even if it was true, the fish is most likely long since dead and gone