Is your filter intake below the gravel?
You should really cut it down and get the pyramid piece a couple inches about gravel..
Unless you want to goAsian, then its rasboras, loaches and gouramis! LOL
Rasboras, loaches and gouramis are Asian, so for an Asian theme biotrope you would use those fish. Cories tetras and ram are Amazonian or S American themed biotrope fish.