you have a lot of options you could go with any number of tetras or barbs problem about a school of 4 or so. Maybe a few more gouramis, like Flame or sunsets. You could try killis, silver hachets, platys. guppies, maybe a redtail shark, udsidedown cats, corys, some kindas of botia and loaches, mollies. its really just what you like. I would suggest getting rid of the common pleco and find a one that gets around 4in or maybe get a few otto cats they do wonders on a 30g. just my opinion.