Have you been testing the rio for ammonia and nitrite?
You said in another thread it had only been set up a few days and you had added a filter starter. The filter starter is very very unlikely to have done anything at all, and you will be in a fish-in cycle. This will take more than three weeks to complete. You should be testing daily for ammonia and nitrite and doing a water change if you see a reading for either of them.
The only reason I said to move the fish into this uncycled tank is that they were in an even worse situation before with an angel, killifish, molly, tetras, cories and a betta all crammmed into a 19 litre tank. Moving them all except the betta into the rio was better than leaving them all there, but it was still not an ideal thing to do.
Your tank will not be cycled in three weeks. You should not get any shrimps until it has been cycled, and then wait another month after that.
And your angel and killifish (thanks Welshweeks) will probably eat any shrimps.