I just took a look at Seriously Fish for cuckoos, and they suggest a lone one will rarely be seen.
I get the attraction. The Synodontis group are really interesting fish. Hard water, soft water - there's a species for every set of conditions. When I stayed in Gabon, there was a river across the road from our shabby little hotel, and a Synodontis species would graze the edges of a dock in groups of five or six. They were beautiful, active fish about 4 inches in length, but what species and what eventual size I don't know.
Wherever we saw them, or other Synodontis, they were in groups in wider rivers or lakes, and never in brooks. It would seem the Tanganyika one lives similarly.
I think I may have to go for reincarnation to be able to keep all the fish that make me say "wow". If I had large tanks, at least one Synodontis species would be in there. I don't do it because this incarnation of me has too small aquariums.