I like goldfish (Carassius auratus). Some in the aquarium hobby would see them as common or plebian, but I like them. Don’t get me wrong, I like all kinds of tropical fish such as plecos and corys and neons, but I have always had a soft spot for goldfish. I actually prefer the simplicity of the common types. I rescue feeders from pet stores and give them a chance. Right now my biggest is about 4 inches. He started out black but has since turned gold.
I do like the fancy ones, the orandas, moors, reiku, etc, but i prefer the simple little comets and feeders.
Here is a picture of one of my tanks. The picture quality could be better but it was taken with my fone and fish tend to move around.

There is a simple pleasure I derive from watching them swim around. It is relaxing and has an almost therapeutic virtue to it. More nonsense to come later.