Write the general characters of the class osteichthyes.

Explanation

1. They are marine or freshwater fishes.
2. They have bony endoskeleton.
3. The body is spindle-shaped.
4. The skin is covered by ganoid, cycloid or ctenoid scales.
5. Respiration is by four pairs of gills covered by operculum.
6. Air bladder is present which helps in gaseous exchange (lung fishes) for maintaining buoyancy.
7. They have two chambered heart.
8. They have mesonephric kidneys and ammonotelic.
9. Lateral line sense organ is present.
10. External fertilization is seen and most forms are oviparous e.g. Labeo and Catla.