upside down or right side up catefish?

[sweet thang]

A couple of weeks ago I bought what I was told was an upside down catfish and yeah the thing does swim upside down but I don't think that's what I have.
It is completely identical to the upside down catfish except for one thing.....it isn't light on top and dark on the bottom, it's the reverse and it is approx. 3 or 4 inches big already. It also seems to be nocturnal since it spend 90 percent of it's time hiding in a large rock cave.
Personally I figure it's one of many types of african catfish and I want to keep it regardless I'm just kinda curious as to what kind of little monster is lurking in my tank lol.

Thanks in advance for your help

 

[OrionGirl]

Check Planet Catfish under synodontis family. There are several fish that will display the inverted swimming, all called UDC. Most stay under 4-5 inches. Mine are about 3-4 right now, in just under a year, and show a very wide color variation from all the pics. I have one that is almost completely white from his nose to his pectoral fin--just a very faint hint of splotching.