saw one for sale today. a black tiger oscar. nice looking specimen too. very bright vivid orange and deep black, just no anal fin. they was no scar, no nothing just SMOOTH. had to be a mutation. i think im going to go get him tomorrow.
In one of the spawns of my oscar pair I noticed 2 or 3 of the babies between ~1000 had no anal fin. seems a genetic disorder.
I don't think it causes problems later.