Class : Osteichthyes

This class includes fishes with bony endoskeleton. Fins also have bony rays.

Habitat: They are found in both marine and fresh water habitats.

Examples:

Marine Freshwater Aquarium
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Exocoetus (Flying fish) Labeo (Rohu) Betta (Fighting fish)
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Hippocampus (Sea horse) Clarias (Magur) Pterophyllum (Angel fish)

Body characteristics:

  • Their body is streamlined.
  • Mouth is mostly terminal.
  • They have four pairs of gills which are covered by a bony operculum on each side.

  • Skin is covered with cycloid/ctenoid scales. Some species do not have scales.
  • They bear lateral line sense organs.
  • Air bladder is present which regulates buoyancy.
  • Heart is two chambered (one auricle and one ventricle).

Physiology: They are cold-blooded (poikilothermic) animals.

Notochord: Endoskeleton (notochord and cranium) is made of bone.

Reproduction: Sexes are separate. Fertilisation is usually external. Claspers are absent. They are mostly oviparous and development is direct.