They'd really prefer more of their own kind. There are freaky looking albino variations of them if you'd like a little more variety. If you have a bigger group then generally they'll just pick on each other instead of harrassing the other fish. These can be murderous on plants too, IME, so stick to tough leaved ones like java fern, hornwort, and anubias. Those 10g's often don't have very good lighting as sold anywho so those would be good choices in any event. They are really nice active, attractively marked tets once they settle in, but they do get a bit bigger than many of the other common tetras though, so you might want to rethink them...
Psst...give your corys some more buddies too!
One more thought! If you are cycling with fish (as opposed to the fish-less method from the other thread), you'll need to take it slow with adding new fish in!