"Man Made" can mean a lot of things.
Line breeding is a "Mad Made" process that takes qualities found in native fish and selectively chooses partners to breed together to bring out or exaggerate those traits. In the wild, every now and then a specimen will have slightly longer than normal fins. Breed two of those together and their offspring has a higher yield of slightly longer finned fish, and that brood is more likely to have a specimen with even longer fins. Do that 300 times and you have long fined Oscars.
I'd suspect the same happened with our Red Oscars. Where a slight amount of red is found in a small percentage of the native population of a local. They were line bred with each other such as described above and next thin ya know, Red Tiger Oscars. Then we start mixing line bred fish such as mixing patternless with Red and we have Red Oscars.
I have no knowledge of the specific details of who, when or how they did this in Oscars.
Line breeding can become muddy when we introduce another species to bring in an outside trait. A fish who has 99 ancestors that are of a single species and 1 that is different, is mostly that species, but is actually a hybrid. We saw that a lot in the earlier days of the hobby when fewer species were formally described and when tracking lineages was done less rigorously.
Then, there is the version of "Man Made" where scientists enter a lab to make alterations.
When we say "Man Made", in my opinion, we should be more specific. Because we may mean, "Line Bred" but someone else may hear "Genetically Manipulated In a Laboratory."