Like the title states, are there any riverine synodontis species suitable for a 20g long for life? I have to downsize and would like to keep my congo tetras and add african riverine catfish to continue my biotope set-up. I know nigriventris stay small but they also need to school and from what I understand a school would require a 55g+. Just wondering if there were other options since my catfish knowledge is admittedly low. Thanks in advance 
