Class Teleostomi is divided into two sub-classes.

a) Sub-Class-1: Crossoptenygii

• The Crossopterygii is characterized by the presence of lobe-like paired fins covered with scales.
• There are two dorsal fins.
• The internal nares are present.
• This subclass is not represented in Nepal.
  • Latimeria
• In this sub-class bony fishes are included which show lobed and massive fins.

b) Sub-class 2: Actinopterigii

• These fishes will live in freshwater or marine water. They do not show internal nostrils. This subclass is divided into three superorders.
• The Actinopterygii is characterized by a ingle dorsal fin in lower forms.
• The internal nares are completely absent.
• The external nostrils are present relatively high up in the head.
• One or two dorsal fins are present.
• Body covered with cycloid, ctenoid, and ganoid type of scales or naked.
• The scales are not of cosmoid type.

Note: Berg (1947) has divided the sub-class Actinopterygii into a series of about 59 orders. Out of these only 11 orders are represented in fresh water of Nepal. At present a total of 182 species belonging to 93 genera under 31 families and 11 orders exist in natural water bodies of Nepal.

i) Order 1. Clupeiformes:

• The fishes of this order have generally keeled abdomens with single serration.
• The anal fin is short.
• The gill membrane is completely free.
• The abdomen has scutes.
• The lateral line is absent.
• Family: Clupeidae Ex. Gudusia chapra (Suia- Nepali)
• Family: Engraulididae Ex. Setipinna phasa (Gankabai-Nepali)

ii) Order 2. Cypriniformes:

• The body is oblong, and compressed with small to large scales.
• The head is without scales.
• The mouth is usually protractile and always toothless.
• There is a single dorsal fin. There is no adipose fin except in conditions.
• The pelvic fins are usually abdominal in location.
• The lateral line is present in the majority of fishes.
• Fishes belonging to this order are called major or minor carp.
• Family: Cyprinidae E.g. Labeo rohita (Rohu- Nepali), L. dero (Gurdi), Catla catla (Catla or Bhakur), Cirrhinus mrigala (Naini or mrigal), Tor tor or Tor putitora (Sahar), Neolissocheilus hexagonolepis (Katle), Puntius chola (Sidre or Pothia), Garragottaa (Buduna), Barilius vagra (Faketa), Schizothorax richardsoni (Asla), Chela laubuca (Deduwa), Brachydanio rerio (Zebra), etc.
• (Brachydanio rerio is the smallest fishinf Nepal. Maximum size is 26 mm).
• Family: Cobitidae E.g. Botia almorhae (Baghi), B. lohachata (Getu or Baghe)
• Family: Bolitoridae E.g. Nemacheilus corica (Gadela)
• Family: Psilorhynchidae E.g. Psilorhynchus balitora (Tite Machha), P. Sucatio

iii) Order 3. Anguilliformes

• The fishes included in this order have cylindrical, much elongated, and serpentinebodiesy.
• The dorsal fin is without a spine. Dorsal and anal fins are very long and usually confluent behind.
• The origin of the dorsal fin is far behind the pectoral origin. Minute scales are present on the body.
• Gill openings are situated in the pharynx in the form of moderate slits near the base of the pectoral fins.
• Family: Anguillidae Ex:Anguilla bengalensis, (Rajbam), Anguilla anguilla.

iv) Order 4. Beloniformes :

• The members of this order have upper jaw and lower jaw well produced.
• The body is elongated but cylindrical.
• The pectoral fins areelongatede and winglike.
• The dorsal fins nareplaced far posterior of the body without spines.
• Both jaws are extended into long beaks with sharp teeth.
• Family: Belonidae Ex: Xenetodon Cancilla (Chuche bam or Kauwa machha)

v) Order 5: Symbranchiformes:

• The body is cylindrical, much elongated, and eel-shaped or snake-like devoid of scales and tapering towards the tail region.
• The air bladder is completely absent.
• The dorsal and anal fins are vestigial or absent.
• The pectoral and pelvic fins are present or absent.
• The scales (when present) are small, oval, and confined to the caudal region.
• The gill openings are confluent and there is a single transverse gill slit on the ventral surface.
• The eyes are small or degenerate.
• Respiration is chiefly buccopharyngeal and cutaneous.
• Skin with mucous glands.
• Barbells are absent.
• Family: Synbranchidae Ex. Monopterus cuchia (Andha bam),
• Family: Mastacembelidae Eg. Mastacembelus armatus (Bam), Macrognathus pancalus (Bam).

vi) Order 6. Perciformes:

• The scales are present on the head and body.
• In some fishes (Channa), the head is covered with plate-like scales.
• The jaws are provided with teeth.
• Accessory respiratory organs are present.
• Some fishes climb trees, or it is called climbing perch.
• The dorsal fin mostly occurs in two parts: one spinous and the other with soft rays, continuous or separate.
• The pelvic fins are thoracic and sub-abdominal with or without spines.
• The caudal fin is forked or absent.
• Family : Ambassidae/ Chandidae E.g. Chanda nama (Nata or Channa)
• Family: Anabantidae Eg: Anabas testudineus (Kabai or Climbing perch)
• Family: Belontidae E.g. Colisa fasciatus (Kotari), C. lalia, C. sota.
• Family: Channidae E.g. Channa punctatus (Bhoti or Garai), C. marulius (Bhaura), C. striaus (Saura)
• Family: Gobidae E.g. Glossogobius giuris (Bulla)
• Family: Gobidae E.g. Glossogobius giuris (Bulla)
• Family: Nandidae Nandus nandus (DHewari)
• Family: Sciaenidae Johnius cottor (Bhola), Channa sps. (Hile machha)

vii) Order 7. Tetradontiformes :

• The body is sort of rounded and globular in an inflated condition.
• The skin covering or scales are modified into small or large spines.
• The gill slits or openings are restricted to lateral slits.
• The teeth are fused into a beak-like dental plate.
• The nasal organ is a short rounded tube with a terminal opening.
• The air bladder is present or absent.
• Ventral fins absent.
• All fins are rounded in shape.
• Head and body covered with ggreenish-blackcolor.
• Family: Tetraodontidae Ex: Tetradon cutcutia (Phokcha or Phulaha Machha), Diodon (Porcupine fish).

viii) Order 8. Cyprinodontiformes:

• The body is short or compressed with scales.
• Scales are present on the head and tail region.
• The upper jaw is protractile in many species.
• The adipose fin is absent.
• Small-sized fishes with ventral fins abdominal.
• There are no spines in the dorsal and anal fins and single dorsal fins.
• Caudal fins are rounded.
• The lateral line system is chiefly on the head; not on the body.
• Larvivorous inhabit.
• White spot on the head region.
• Family: Aplocheilidae E.g. Aplocheilus puanchax (Tikuli machha)
• Family: Poecilidae E.g. Gambusia afinis

ix) Order 9. Osteoglossiformes:

• The body is broad, sand strongly compressed with fine scales on the head as well.
• The ventral fins are much reduced.
• The dorsal fin is short.
• The anal fin is very long.
• The anal fin is much elongated and confluent with a small caudal fin. The caudall region is long and tapering.
• Maxillaries are well toothed forming the greater part of the upper jaw.
• Pectoral fins are depressed.
• The barbells are absent.
• The lateral line is present.
• Body covered with minute cycloid scales.
• Family: Notopteridae Ex: Notopterus notopterus (Golhai) Notopterus chitala (Chitala) Chitala chitala (Moi)

x) Order 10. Mugiliformes:

• The body is oblong to elongate, compressed, and may be depressed anteriorly to a little extent.
• There are two dorsal fins which are short and widely separated, first with spines.
• The pelvic fins are sub-abdominal with a spine.
• The lateral line is absent.
• It is represented by only one family and 2 fish species in Nepal.
• Family: Mugilidae Eg: Sicamugil caucasian (Rewa), Rhinomugilcorollaa.

xi) Order 11. Siluriformes:

• The body is naked or with bony plates (Scutes), never with true scales.
• The maxillae are usually much reduced serving as bases of maxillary barbells. Nearly one to four pairs of barbells are present.
• The first ray of the pectoral and last ray of the dorsal fin is modified as hard pungent spines or thick rays.
• The dorsal fin enlarges in some species while other adipose fins are also present.
• Carnivorousinhabitt.
• Poison glands are present in some species in the base of the pectoral region.
• Accessory respiration organs are present in some species.
• Barbells are long and filamentous.
• Ex: Wallago attu, Heteropneustes fissilis etc.
• Family: Amblycipitidae E.g. Amblyceps mangois
• Family: Bagridae E.g. Mystus bleekeri (Tengra), M. tengara (Tengri), Rita rita (Rita or Belaunda)
• Family: Chacidae E.g. Chaca chaca (Kircire or Pauwa)
• Family: Claridae E.g. Clarias batrachus (Mangur or Mungri)
• Family: Heteropneustidae E.g. Heteropneustes fossilis (Singhi or Kande)
• Family: Olyridae E.g. Olyra longicaudata
• Family: Scheibeidae E.g. Ailia coila (Sutara or Patanga), Clupisoma garua (Jalkapur)
• Family: Siluridae E.g.Wallago attu (Buhari), Ompok bimaculatus (Lalmuha or Chachara)
• Family: Sisoridae E.g. Bagarius yarellii (Gonch or Thend), Gagata sexual (Tengana), Glyptothorax indices (Kotel), Sisor rhabdophoru

xii) Order. Salmoniformes:

• Long cylindrical body.
• Head region absence of scales.
• Fishes are carnivorous in habit.
• An adipose fin present.
• The body is covered with seven different colors mainly dominant black of brown dotted color.
• The lateral line is complete.
• Large opening of mouth absence of barbells.
• Oncorhynchus mykis, Salmo trutta, etc.