Which fish has 20 families and 111 genera?

There's no fish that specifically has exactly 20 families and 111 genera. This kind of classification is constantly evolving and depends on the specific taxonomic system being used.

However, it's important to note that:

* Fish is a very broad category: It includes a vast array of species, from tiny guppies to massive whales.

* Taxonomic classifications change: New discoveries, genetic studies, and revisions by scientists constantly lead to changes in the classification of fish.

To find out more about the families and genera of a specific type of fish, you'd need to specify the group you're interested in. For example, you could ask about the families and genera of:

* Sharks: These are part of the class Chondrichthyes.

* Eels: These belong to the order Anguilliformes.

* Salmon: These are part of the family Salmonidae.

Let me know if you have a specific type of fish in mind, and I can help you find more information about its classification!