Also, from the angle of your photo, it appears that your decorative log takes up a good portion of the tank and limits your Oscar’s ability to swim around the entire 75G tank. If this is the case, I would recommend removing the
log. Also what is the deal with the unsightly algae/brown vegetable matter floating on the surface of the aquarium? It gives the impression you are not doing routine aquarium maintenance and is probably why you received such a negative initial response. Thanks for rescuing the Oscar and giving him a better environment than he previously had, but it seems like you have the ability and resources to do even better for him.
