10 mixed size isopods.
Parvus are a small and shy isopod, maxing out at 1/3" or so, but don't underestimate them. They are little workhorses. They spend the majority of their time underground, and once established produce quickly, making them great for bio active set ups as they are small enough and shy enough to get the work done and avoid getting eaten. They are also super colorful, coming in a variety of shades.