This document provides an overview of fish classification systems presented by Nelson in 1984 and updated in 2016. It outlines the major taxonomic groups of fish, including jawless fish (hagfish and lampreys), cartilaginous fish (sharks and rays), and bony fish classified into ray-finned fish and lobe-finned fish. The updated 2016 classification separates hagfish from other fish and divides bony fish into two subclasses based on fin structure.

1. FISH CLASSIFICATION
PRESENTED BY HADIA KHADIJA
ID#04021613013
BS-ZOOLOGY (VIII)
Department of Zoology, QAU Islamabad

2. OUTLINE
• INTRODUCTION
• CLASSIFICATION BY NELSON-1984
• CLASSIFICATION BY NELSON-2016
• REFRENCE

3. INTRODUCTION
• Fish are aquatic vertebrates with gills and fins rather than lungs and
legs.
• Fish represent huge diversity in shape, size, color, and habitat.
• In geologic time they preceded the other vertebrate groups which are
derived from them.

4. INTRODUCTION
• Fish share with vertebrates a basic body plan of bilateral symmetry,
with a dorsal supporting structure the notochord as a precursor to
the series of harder vertebrae.
• Currently, fish are the most numerous vertebrates representing
roughly 50 percent of al vertebrate species now alive.
• In 2016, Nelson reported 32,000 species of Fish.

5. CLASSIFICATION BY NELSON-1984
Phylum Chordata
Subphylum Vertebrata (Craniata)
Superclass Agnatha (Jawless Fish)
Class Cephalaspidomorphi
Subclass Cyclostomata
Order Myxiniformes (Hagfishes)
Order Petromyzoniformes (Lampreys)

6. AGNATHA-JAWLESS FISHES
Order: Myxiniformes
Family: Myxinidae
Genus: Eptatretus
Species: E. stoutii (Pacific hagfish)
Order: Petromyzontiformes
Family: Petromyzontidae
Genus: Petromyzon
Species: P. marinus (sea lamprey)

7. CLASSIFICATION BY NELSON-1984
Phylum Chordata
Subphylum Vertebrata (Craniata)
Superclass Gnathostomata (Jawed Fish)
Class Chondrichthyes (Cartilagnous Fish)
Subclass Holocephali
Order Chimaeriformes (chimaeras)

8. CLASSIFICATION BY NELSON-1984
Phylum Chordata
Subphylum Vertebrata (Craniata)
Superclass Gnathostomata (Jawed Fish)
Class Chondrichthyes
Subclass Elasmobranchii (sharks and rays)
Order Heterodontiformes (Port Jackson shark)
Order Hexanchiformes (cow shark)
Order Squaliformes (dogfish)
Order Lamniformes (basking shark, mackerel shark)
Order Rajiformes (rays)

9. GNATHOSTOMATA-JAWED FISHES
Subclass: Holocephali
Order: Chimaeriformes
Family: Chimaeridae
Genus: Hydrolagus
Specie: H. colliei
Chimaeras
Subclass: Elasmobranchii
Order: Heterodontiformes
Family: Heterodontidae
Genus: Heterodontus
Specie: H. portusjacksoni
Port Jackson shark
Subclass: Elasmobranchii
Order: Hexanchiformes
Family: Hexanchidae
Genus: Hexanchus
Specie: H. griseus
Cow shark

10. GNATHOSTOMATA-JAWED FISHES
Subclass: Elasmobranchii
Order: Squaliformes
Family: Squalidae
Genus: Squalus
Specie: S. acanthias
Dogfish
Subclass: Elasmobranchii
Order: Lamniformes
Family: Cetorhinidae
Genus: Cetorhinus
Specie: C. maximus
Baskingshark
Subclass: Elasmobranchii
Order: Rajiformes
Family: Aetobatidae
Genus: Aetobatus
Specie: A. narinari
Spotted eagle ray

11. CLASSIFICATION BY NELSON-1984
Superclass Gnathostomata
Class Osteichthyes (Bony Fish)
Subclass Crossopterygii
Order Coelacanthiformes (Latimeria)
Subclass Dipneusti (lungfishes)
Order Ceratodontiformes
Order Lepidosireniformes
Subclass Brachiopterygii (bichirs)
Order Polypteriformes (Polypterus)

12. GNATHOSTOMATA-JAWED FISHES
Subclass: Dipnuesti
Order: Ceratodontiformes
Family: Neocrodontidae
Genus: Neoceratodus
Specie: N. forsteri
Queensland lungfish
Subclass: Dipnuesti
Order: Lepidosireniformes
Family: Protopteridae
Genus: Protopterus
Specie: P. aethiopicus
Marbled lungfish
Subclass: Brachiopterygii
Order: Polypteriformes
Family: Polypteridae
Genus: Polypterus
Specie: P. delhezi
Polypterus
Subclass: Crossopterygii
Order: Coelacanthiformes
Family: Latimeriidae
Genus: Latimeria
Specie: L. chalumnae
Latimeria

13. CLASSIFICATION BY NELSON-1984
Superclass Gnathostomata
Class Osteichthyes (Bony Fishes)
Subclass Actinopterygii (ray-finned fishes)
Order Acipenseriformes (sturgeons and paddlefish)
Order Lepisosteiformes (gars)
Order Anguilliformes (eels)
Order Cypriniformes (carps, suckers, and loaches)
Order Salmoniformes (salmon)

14. GNATHOSTOMATA-JAWED FISHES
Subclass: Actinopterygii
Order: Lepisosteiformes
Family: Lepisosteidae
Genus: Lepisosteus
Specie: L. oculatus
Spotted gar
Subclass: Actinopterygii
Order: Anguilliformes
Family: Angullidae
Genus: Anguilla
Specie: A. Anguilla
European eel
Subclass: Actinopterygii
Order: Acipenseriformes
Family: Acipenseridae
Genus: Acipenser
Specie: A. oxyrinchus
Sturgeon

15. GNATHOSTOMATA-JAWED FISHES
Subclass: Actinopterygii
Order: Cypriniformes
Family: Cyprinidae
Genus: Cyprinus
Specie: C. carpio
Common carp
Subclass: Actinopterygii
Order: Salmoniformes
Family: Salmonidae
Genus: Salmo
Specie: S. sala
Atlantic salmon

16. CLASSIFICATION BY NELSON-1984
Superclass Gnathostomata
Class Osteichthyes (Bony Fishes)
Subclass Actinopterygii (ray-finned fishes)
Order Beloniformes (flying fishes)
Order Lophiiformes (anglerfishes)
Order Siluriformes (catfishes)
Order Gasterosteiformes (sticklebacks)
Order Tetraodontiformes (triggerfish)

17. GNATHOSTOMATA-JAWED FISHES
Subclass: Actinopterygii
Order: Lophiiformes
Family: Lophiidae
Genus: Melanocetus
Specie: M. johnsonii
Humperback anglerfish
Subclass: Actinopterygii
Order: Siluriformes
Family: Siluridae
Genus: Silurus
Specie: S. melas
Black bullhead catfish
Subclass: Actinopterygii
Order: Beloniformes
Family: Exocoetidae
Genus: Parexocoetus
Specie: P. brachyterus
Sailfin flying-fish

18. GNATHOSTOMATA-JAWED FISHES
Subclass: Actinopterygii
Order: Tetraodontiformes
Family: Balistidae
Genus: Balistapus
Specie: B. undulatus
Orange-lined triggerfish
Subclass: Actinopterygii
Order: Gasterosteiformes
Family: Gasterosteidae
Genus: Gasterosteus
Specie: G. microcephalus
Sticleback

19. CLASSIFICATION BY NELSON-2016
• Nelson and colleagues separated the hagfish from the lampreys and all
other extant fish on the basis of lack of any vertebral elements in hagfish.
• There is a small group of ‘relict fish’ (lungfish, coelacanth, and bichirs)
which show a variety of primitive characteristics indicating their status as
remnants of very ancient lineages.
• Class Osteichthyes now have two Subclasses.
 Subclass Actinopterygii (most bony fish)
 Subclass Sarcopterygii (bony fish species close to terrestrial vertebrates)

20. CLASSIFICATION
BY NELSON-
2016
Phylum Chordata
Subphylum Craniata
Infraphylum Myxinimorpha (Hagfish)
Infraphylum Vertebrata (Vertebrates)
Superclass Petromyzontimorphi (Lampreys)
Superclass Pteraspidomorphi
Superclass Anaspidomorphi
Superclass Thelodontimorphi
Superclass Osteotracomorphi
Superclass Gnathostomata (Jawed Fish)
Class Chondrichthyes_ according to old classification
Class Osteichthyes
Subclass Actinopterygii
Subclass Sarcopterygii

21. REFRENCE
BOOK: ESSENTIAL FISH BILOLOGY: Diversity, Structure, and Function
AUTHORS: DEREK BURTON AND MARGARET BURTON

22. THANK YOU