Hmm, it's a toss-up between Synodontis petricola and Aethiomastacembelus plagiostoma. (Small, active schooling catfish, and beautifully colored/patterned spiny eels from Lake Tanganykia.) S. eupterus was my favorite, had one for almost 10 years, but I've wanted to breed Synodontis catfish in an aquarium longer than that, and it's difficult and unlikely with eupterus.