Yes, but with 20 gallon, be careful of your
GBR stocking. I had two bolivian rams (closely related) that one would stress out the other, so I put them in two separate tanks. Maybe one BN pleco (high waste-producers), some corys, and 1 GBR? I'm not saying that two GBR's couldn't be in a 20 gallon, but you may want to have a backup plan just in case.
Others may have had better results in a 20 gallon, so feel free to wait for others to come along and share their opinions and experiences.