I've just set up a 1.5 gallon pico tank and I am on the fence as to what I'd put in there (if anything at all) definitely too small for fish but shrimp/snails... maybe? I have a big colony of cherries in 2 tanks and they are happy just to be searching for food often in just a small area but its our perception of how much space we want to give them rather than whats fair... I did ponder moving a few shrimplets to it and moving them out as they grow but not sure...Assuming you planted heavily and did water changes daily, would it be viable to keep say 4/5 cherry shrimp in such a tank long term...