I am currently running a 10 gallon with a marineland penguin biowheel 100 on it with extra sponges. It is IMO heavily planted. So far I have 4 otos and 10 ember tetras in it. Would I be able to add a small school of 5-6 Pygmy cories? I wasn't going to add anything else but my LPS has them in and they are soooooo cute and tiny!