Such a great thread to read! I have seen this happen a couple times with oscars. Being a oscar lover it always makes me sad to see a careless owner "releasing" them into local waterways then even sadder when they are caught by fishermen. I mean it's best for the environment but I still feel bad for the fish even being in that situation.
But I'm a goldfish lover, I have a 55gal with a calico Ryukin. He only has 1 eye, I'm not sure how he lost it but it happened before he came to live with me, and his name is patches. He is awesome. He is currently only about 1inch long, I hope he gets as big as the black moor you found someday.
I'm glad it all turned out good for you and the fish!