I have a 55 with two 6in albino oscars, one is tiger the other albino is just solid gold(not even a tail spot) a pelico and a 3 in fully grown red zebra (african) its worked for 5 months now but im afraid that eventually they will eat my red zebra...

Welcome to the forum. I am not going to start lecturing you but your tank is only big enough for one Oscar. If you put two Oscars plus potential food in such a small space, and you are asking for trouble, both aggression and Oscars eating the other fish given half a chance. Can't really say any more than that

I did a partial water change and since my male tiger albino oscar is picking on the albino female and she hides every chance. prior to this they have been best buds, even mated before (eggs never hatched). They always swam side by side, now he is attacking her ev oppurtunity since the water change.

Don't be too concerned just for the moment. Oscars do occasionally have a bit of a ruckus between each other. Hopefully, tomorrow they will be fine. If they have been fine up until now, there is no reason to think that they have suddenly changed. If, for some very strange reason they have suddenly become enemies and fight all the time than he might have to think about separating them but cross that bridge if you come to it. You'll probably find tomorrow they'll be perfectly okay. Water changes can be very stressful for fish so you'll probably find that is why they are acting strangely.