This document summarizes the key characteristics of 18 orders of bony fishes (class Osteichthyes) based on their anatomical features and examples. It describes traits such as fin structure, scale type, presence of swim bladders and their connections to other organs, body shape adaptations, and example fish from each order. The orders discussed include Crossopterygii, Dipnoi, Polypteriformes, Acipenseriformes, and others.

1. Class: Osteichthyes
By- Sanju Sah
St. Xavier’s College, Maitighar, Kathmandu
Department of Microbiology

2. Order: Crossopterygii
-Extinct.
-Paired lobate caudal
fins. 3 lobed.
-Crossoi : fringe.
-pteryx : fin.
Eg: Latimeria

3. Order: Dipnoi
• Di – double , Pnoe – breathing.
• Air bladder single or paired.
• Lung like air bladder.
• Eg: all lung fishes.
Protopterus

4. Order: Polypteriformes
• Poly : many , pteri : fins.
• Presence of 8 finlets in dorsal fin.
• Lobed pectoral fins.
• Eg: Polypterus

5. Order: Acipenseriformes
• Cartilaginous fishes.
• Scaleless fishes.
• Body covered with 5 pairs of
Bony scutes.
• Endocranium is cartilaginous.
Eg: Acipenser

6. Order: Amiformes
• Thin overlapping cycloid scales.
• Premaxillary firmly articulated
with cranium.
• Eg: Amia

7. Order: Semionotiformes
• Snout and body elongated.
• Scales rhomboid , gonoid in
oblique rows.
• Eg: Lepidosteus

8. Order: Clupeiformes
• Well developed cycloid scales.
• Homocercal caudal fin.
• Werberian apparatus present.
• Air bladder connected with ear.
• Eg: Salmo

9. Class: Scopeliformes
• Presence of second dorsal fin
or adipose fin.
• Usually luminous organs present.
• Mouth with numerous teeth.
• Swim bladder absent.
• Eg: Harpodon

10. Class: Cypriniformes
• Air bladder with duct to
Pharynx.
• Werberian ossicles present
connecting ear and Air bladder.
• Air bladder also connected with
Alimentary canal.
• Eg: Labio

11. Class: Anguiliiformes
• Snake like fish.
• Scales vestigial or absent.
• Long dorsal and anal fin.
• Air bladder connected with intestine.
• Anguilla

12. Class: Beloniformes
• Elongated body.
• Cycloid scales.
• Ventral fins shifted to abdominal
sides.
• Some can fly.
• Exocoetus, Cypselurus

13. Class: Syngnathiformes
• Swim bladder closed.
• Protective bony rings.
• Tubular snout.
• Males with brood pouch.
• Hippocampus

14. Class: Ophiocephaliformes
• Ophio- snake, Cephalus- head.
• Cycloid scales.
• Depressed head.
• Accessory respiratory organ.
• Ophiocephalus

15. Class: Symbranchiformes
• Sym- jointed, branchia- gills.
• Eel like body.
• Gill slits jointed to form
transverse ventral slites.
• No air bladder.
• Symbranchus

16. Class: Mastacembeliformes
• Eel like body.
• Free spines infront of dorsal fin.
• Dorsal, anal and caudal fins united
to form A continuous fin.
• Mastacembelus

17. Class: Perciformes
• Perci- spines.
• Fins with spines.
• 2 dorsal fins.
• Werberian apparatus absent.
• Air bladder without duct.
• Anabas

18. Class: Scorpereniformes
• Enlarged head and pectoral fin.
• Spines projecting from gill
covering.
• Pterois

19. Class:Pleuronectiformes
• Bottom dwellers.
• Flat body. Lying on one side.
• Swim bladder absent.
• Both eyes on dorsal side.
• Synaptura

20. Class: Echeneiformes
• First dorsal fin modified
into flat oval adhesive disc.
• No air bladder.
• Echeneis

21. Class: Tetraodontiformes
• Strong jaw with sharp beak.
• Spiny scales usually present.
• Some inflate by swallowing water.
• Tetrodon

22. Thank You !