There are hundreds of different species labelled "upside down catfish", most are Synodontis. S. nigriventris is the smallest, they grow to around 3-4", and are peaceful schooling fish.
There is one species that isn't a Syno, the Asian UD catfish, that is more aggressive than most Syno's. A good tankmate for larger cichlids, but not for smaller fish: http://www.planetcatfish.com/cotm/cotm.php?article_id=115
There is one species that isn't a Syno, the Asian UD catfish, that is more aggressive than most Syno's. A good tankmate for larger cichlids, but not for smaller fish: http://www.planetcatfish.com/cotm/cotm.php?article_id=115
