What tropical fish is all black?

There isn't a single tropical fish that is completely black. While there are many black or dark-colored fish, most have some sort of markings or coloration that breaks up the black.

However, here are some fish that come close to being all black:

* Black Skirt Tetra: This fish has a dark, almost black body with a long, flowing skirt-like fin.

* Black Ghost Knife Fish: This unique fish is silver-black and has a long, flat body that resembles a knife.

* Black Angelfish: This variety of angelfish has a dark black body with hints of orange or red depending on the breed.

* Black Molly: There are several varieties of black mollies, and some are nearly completely black.

Keep in mind that even these fish might have a slight shimmer or subtle pattern under certain lighting conditions.