What Is a Bony Fish?

Bony Fish Facts, Characteristics and Examples

Two bony fish species: Atlantic sailfish attacking a sardine baitball, Isla Mujeres, Mexico
Two bony fish species: Atlantic sailfish attacking a sardine baitball, Isla Mujeres, Mexico. Rodrigo Friscione / Getty Images

About 90% of the world's fish species are bony fish. What does the term bony fish mean, and what type of fish are bony fish?

Two Types of Fish

There are two types of fish - bony fish, and cartilaginous fish. The main thing that sets bony fish apart from cartilaginous fish is the presence of a skeleton made of bone. A cartilaginous fish has a skeleton made out of - you guessed it - cartilage.  Cartilaginous fish includes the sharks, skates and rays.

Other Characteristics of Bony Fish:

Both bony fish and cartilaginous fish breathe through gills, but bony fish also have a hard, bony plate covering their gills. This is called an operculum. They may also have distinct rays, or spines, in their fins. Unlike cartilaginous fish, bony fish have swim bladders to regulate their buoyancy.

Some documents refer to the bony fish as the Osteichthyes, which used to be recognized as a class of organisms.

Osteichthyes is still used commonly to refer to the two main types of bony fish:

Classification of Bony Fish:

There are over 20,000 species of bony fish. 

Evolution of Bony Fish:

The first fish-like creatures appeared over 500 million years ago. Bony fish and cartilaginous fish diverged about 420 million years ago.

Read More About Fish Evolution.

Where Do Bony Fish Live?


Bony fish live in waters around the world. Marine bony fish live in all the oceans, from shallow to deep waters, and in both cold and warm temperatures. An extreme example is the Antarctic icefish, which lives in waters so cold that antifreeze proteins circulate through its body to keep it from freezing.

Of course, there are bony fish that also live in freshwater.  Commonly-fish freshwater species such as sunfish, bass, and catfish are bony fish, as are the freshwater tropical fish that you'd have in an aquarium.  

What Do Bony Fish Eat?

A bony fish's prey depends on the species, but may include plankton, crustaceans (e.g., crabs), invertebrates (e.g., green sea urchins), and even other fish.

How Do Bony Fish Reproduce?

Depending on the species, bony fish may bear live young or lay eggs.

Examples of Bony Fish:

Conjure an image of a "fish," and a bony fish likely comes to mind. Below are some species that are bony fish: