Ganoid fish are a type of bony fish that is characterized by having scale-like structures on their skin. These scales are made up of a tough, protective material called ganoin. Ganoid fish are some of the oldest fish in existence, with fossils dating back over 300 million years. There are only about 100 species of ganoid fish alive today, compared to the 30,000 or so species of other bony fishes.
Ganoid fish live in both fresh and salt water environments. Some popular examples of ganoid fish include the sturgeon, paddlefish, garfish, and bowfin. These fish are often predators, feeding on smaller fishes and invertebrates. Many ganoid fishes have large mouths and sharp teeth that help them capture their prey.
Ganoid fishes are interesting creatures because they have a number of unique physical features. For example, most ganoid fishes have a swim bladder that helps them regulate their buoyancy in water. This organ is not found in any other type of fish. Additionally, many ganoid fishes have an ability to produce light using cells called photophores. This process is known as bioluminescence and it can be used for communication or camouflage purposes.