Tiger barbs are basically unpredictable.
In large enough numbers, they are peaceful towards other fish. I'd day 8+ in your tank.
Only add bamboo shrimp if you are prepared to target feed them small particled food every couple of days using a syringe or pipette, crushed flake works well.
Otherwise they seem to either slowly die or wreck their fans trying to look for food on the ground.
You also need to make sure the shrimp will have a few options of places to hide in (where fish wont go) for when they shed their skin. Otherwise they can be attacked and critically injured at this time,