E. bleheri is a very common sword species and doesn't require too much in the way of lighting. It's also tough. Unfortunately, it's not tough enough for an oscar. I don't think any plant is. Even if the oscar didn't tear them apart, he would constantly be uprooting them with his digging habits. I've kept oscars before, and the simple truth is that no live plants will endure them for long. Well, floating plants would, but nothing rooted.
hey, if it doesn't work out I can always move the oscar. No big deal.
Here's a list I've been generating of "maybe" plants to keep. I wouldn't keep all of these.
Pennywort (Hydrocotyle leucocephala
Baby Tears Micranthemum Umbrosum
Cryptocoryne Wendtii De Witt
Saggitaria Broad Leaf (platyphylla)
Echinodorus Horemanii (Green)
Green Ozelot Sword(Ech. Ozelot)
Bolbitus (Fern) (Heudelotti) (Medium green fronds)
Moss Balls (Chladophora Aegagropila)
Gymnocoronis Spilanthoides (New!) (South America)
Pennywort (Hydrocotyle leucocephala)
Giant Hygro (Hygrophila corymbosa)
Micro Sword (Lilaeopsis nova-zelandiae)
Pygmy Chain Sword (Echinodorus tenellus)
Giant Hairgrass (Eleocharis montevidensis)
Cryptocoryne walkeri (lutea)