I have a 46 gallon with a biowheel 350 and a Aquaclear 30. My tank inhabitants are 6 adult guppies, 4 juvenile guppies, about 60 fry, 3 bumblebee platys, 4 Cory cats and 2 African dwarf frogs. I added 2 of the cories and 3 of the platys a few days ago. I noticed yesterday one of my old cories...