jaguar cichlid and oscar together?

Never possible even if in a bigger tank.If you were to ever put them in the same tank at all get a 200+ gallon tank. Then you shouldn't have much of a big problem and terroities would be estashblished and you shouldn't have a big problem maybe a run in every once in a while during feedings or just swimming around.Jag's are super aggressive and could kill an,Oscar of equal to somewhat bigger stature.Just be careful if you dare to do that...

its fine

Too risky considering that an Oscar alone should be in at least a 55 gallon tank, and a 75 just makes him more comfortable, now you think about adding in a much higher, and bigger aggressive cichlid, no, I think not. In the end, it'll be one or the other in that tank only, or if one doesn't kill the other, the milder or weaker one will live one miserable life in that. Why don't you just wait until you get the bigger tank? I mean, it's not like either one of those species are going to be extinct in a year or so. No sense to even play with fire.