- Members of class Osteichthyes have four pairs of gills which are covered by an operculum on each side.
- Air bladder is present which regulates buoyancy.
- Heart is twochambered and they are cold blooded animals.
- Sexes are separate, fertilization is usually external,they are mostly oviparous and development is direct.
- The body is streamlined.
Examples- Marine – Exocoetus (Flying fish),
Freshwater – Clarias (Magur)
Aquarium – Betta (Fighting fish).
Fig. flying fish
Fig. Fighting fish