It is a common pleco

hmmm, I dont think so, because it has big whiskers, and doesnt suck on the glass or anywhere else. Just eats the fish food I dump in.

Definitly Synodontis, not sure which one as there are many different species and many are brown with black spots.
They originate in Africa with many coming from the Rift Lakes. They have long lives and are fairly easy to keep.
Over the years, I've had about 10 different species but Synodontis Angelicus has been my favorite. I don't see them in the stores any more but in the 1970's they were available occasionally, mostly wild caught. They came in with wild caught African Cichlids almost as an afterthought but quite quickly became very popular.

It is a Synodontis nigrita. Yours is a fairly large one, they can reach ten inches or so. At some time yours has lost it's dorsal fin. They are not particularly aggressive to other fish except for their daytime hiding place. It is found in West Africa in rivers including the Congo. It would prefer a pH around 7.0 but it is not important. They eat most foods and will eat some plant material in addition to flakes and some frozen foods like bloodworms or brine shrimp.

Thanks Papa, He probably rubbed that fin off squeezing in and out of that log he lives inside of. I almost never see him because he is always hiding! He seems depressed and lonely, but I could be projecting my human emotions on him. I will buy him some bloodworms, maybe that will cheer him up!