Aquariums: What fish should I stock?

Hi!
I'm new here and new to the hobby.
This is pretty much my first tank and I'm wondering what should I stock it with. It's an 18G/65L tank and I want to add a school of corys (pygmy/pandas/julii). What fish would go best with them? Preferably peaceful schooling fish.
It currently houses amano shrimps and a few rosy barbs – the latter would be transferred to a pond I'm building since this tank is probably a little too small for them, and they probably wouldn't do well with the corys from what I've read.
The tank is cycled and with stable parameters, 7.6 pH, room temperature but I'm open to adding a heater, low nitrate due to the terrestrial plants, and water is on the hard side.

Appreciate any kind of input 🙂