Cartilaginous fishes (Chondricthyes)
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Bony fishes (Osteichthyes)
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1. Exclusively marine.
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Marine & fresh water.
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2. Heterocercal caudal fin.
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Homocercal caudal fin.
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3. Cartilaginous endoskeleton.
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Bony endoskeleton
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4. Gill slits without operculum.
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4 pairs of gills covered by an operculum on each side.
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5. Crescent (half moon) shaped ventral mouth
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Terminal mouth
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6. Skin with placoid scales. Teeth are modified placoid scales which are backwardly directed.
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Scales are Cycloid, ctenoid etc.
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7. No air bladder so they have to swim constantly to avoid sinking.
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Air bladder for buoyancy
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8. Sexes are separate. In males pelvic fins bear claspers.
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Sexes are separate. No claspers
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9. Internal fertilization.
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Fertilisation external
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10. Many of them viviparous
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Mostly oviparous
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11. E.g. Scoliodon (Dog fish), Pristis(Saw fish), Carcharodon (Great white shark), Trygon (Sting ray),Torpedo (Electric ray)
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E.g.
Marine fishes: Exocoetus (flying fish),Hippocampus (sea horse), Sardine, Mackeral, Tuna, Remora (sucker fish), Pomfret, Cybium
Fresh water fishes: Labeo (Rohu), Catla(Katla), Clarias (Magur), Tilapia, Anabas(Climbing perch)
Aquarium fishes:
Betta (Fighting fish), Pterophyllum (Angel fish) etc.
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