My Oscar Is Seeing His ReflectionHave you ever seen your Oscar Fish attacking the side of the aquarium, mouth open, flaring gills, shaking its whole body? Worry not, it's probably just a case of the Oscar seeing its own reflection in the glass. Oscar Fish are not the sharpest tools in the box, they are not going to recognise their own reflection, all they are seeing is another Oscar. They will probably think that the reflection is a rival to their domain.
If you don't like seeing your fish stressing out then you could try putting a dark backing on the side and back of the tank, this may stop the fish seeing its reflection. Also, just rearrange the substrate if you see them clearing it away from the bottom of the aquarium.
But like I have already said, there really isn't anything you should worry about if you do observe your fish trying to fight its own reflection in the aquarium glass.