they grow really slow, i see most around 9". My experience with serpae tetras and tiger barbs were horrible, they would nip at everything!!! I wanted to try them out knowing their tendency to nip but it was a risk i wanted to take since they were cheap. I think cory cats would look nice in the set up. If you do add more fish just keep an eye on the serpae and tiger barbs.
i got rid of the plants. im getting a black background this week