A pair of grown Severum would be nice in a 90. I agree with plants not working, I tried Ludwigia, Vals, Crypts, Anubis, Water Sprite (the water sprite was a nightmare, I was netting it out). Mine stayed away from the Java Fern until it was the last man standing and then that got mangled not eated just riped up. What did look nice in the tank and I'm still using it for diggers is the plastic and fabric plants from the reptile section in Petsmart that suction cup to the glass. It looks nice with a black background along the back wall and I stuck a couple up near the top for a floating effect and to create a shaded subdued area.