I changed out the media in my Eheim ecco filter and found 6 or more shrimp of different sizes in the bottom of the canister. They looked healthy living in complete darkness with good water flow and nutrient material. I poured them back into the tank and they looked fine. proves how much of what we do makes no difference to them, i.e lighting, plants, feeding, etc. Who needs a tank, it would be interesting to place a colony in a canister and leave them alone for 2-3 months and watch them take off.