Freshwater Fishes of Iran


Keys - Families

Revised:   07 January 2005

Families     Genera and Species     Regional Ichthyofaunas

A little experience will soon make this key to families redundant as all Iranian freshwater fish families can be recognised at a glance. Separate keys are given for families with two or more species (Genera and Species link above). Only species which I have seen in Iran, examined museum material of, or have reliable literature records for, are included. The survival of breeding populations of some exotic fishes is uncertain; nonetheless these species are included here.

Drainage basins are given for families with a limited distribution; others are widespread, occuring in all or most basins. "Marine" is used here for drainages entering the Persian Gulf and Sea of Oman including the basins of the Tigris River, Gulf, Hormuz and Makran. The families under this heading are marine but have species that regularly enter fresh water in Iran. The terms Tigris River, Gulf, Hormuz and Makran are restricted here for freshwater residents.

Key characters, e.g. fin ray counts, are restricted to the Iranian species and family members from elsewhere may not key out here.

1. Seven lateral gill openings on each side; mouth a sucking disc; no paired (pectoral or pelvic) fins = Petromyzontidae (Caspiomyzon wagneri - Caspian Sea)
    Less than seven gill openings (1 or 5) on each side; mouth normal; at least pectoral fins present, usually pelvic fins also ---> 2

2. Five lateral gill slits on each side; scales placoid (small and prickle-like) = Carcharhinidae (Carcharhinus leucas - Marine)
    One gill opening on each side; scales, when present, cycloid, ctenoid or bony scutes ---> 3

3. Body covered with five rows of bony scutes; mouth inferior, behind long snout, with four barbels in front of mouth = Acipenseridae (Caspian Sea)
    Body without scutes; barbels, if present, not immediately in front of mouth on a long snout ---> 4

4. Chin with a single barbel at mid-point [no fin spines, 58 or more anal and second dorsal fin rays] = Gadidae (Lota lota - Caspian Sea)
    Chin without a barbel;  ---> 5

5. Pelvic fins united to form a disc or funnel = Gobiidae (Caspian Sea, Hari River, Marine)
    Pelvic fins present or absent but not formed into a disc ---> 6 

7. Pelvic fins absent; body very elongate ("eel-like") ---> 8
    Pelvic fins present; body not very elongate ---> 10

8. First dorsal fin comprising 30-35 short, sharp spines; flexible snout tip = Mastacembelidae (Mastacembelus mastacembelus - Tigris, Gulf, Kor)
    Spines lacking in dorsal fin; snout not flexible ---> 9   

9. Body extremely thin; bounded by bony rings; snout tube-like; mouth minute = Syngnathidae (Syngnathus abaster - Caspian Sea)
    Body robust; covered with minute scales; snout not tube-like; mouth large = Anguillidae (Anguilla anguilla) - Caspian Sea)

10. First dorsal fin with either 3 or 8-12 isolated spines = Gasterosteidae (Caspian Sea)
      First dorsal fin not composed of isolated spines, spines when present connected by a membrane ---> 11

11. Nostrils each with a single pore; lateral line in two parts, the  posterior one lower = Cichlidae (Iranocichla hormuzensis - Hormuz)
      Nostrils each with two pores; lateral line a continuous line or absent ---> 12

12. Eyes on same side of body; body compressed with left side lying on bottom = Pleuronectidae (Platichthys flesus - Caspian Sea)
      Eyes on opposite sides of body ---> 13

13. Blunt grinding teeth in jaws = Sparidae (Acanthopgarus latus - Marine)
    Teeth absent or, if present, sharp ---> 14

14. Jaws duck-like with strong teeth; dorsal and anal fins far back on body near tail = Esocidae Esox lucius - Caspian Sea)
      Jaws and fins not as above ---> 15

15. Barbels absent ---> 16
      Barbels present ---> 19

16. First and second dorsal fins widely separate; scales cycloid ---> 17
      First and second dorsal fins continuous or close together; scales ctenoid ---> 18

17. First dorsal fin spines 5 or more (usually 8 or more) and flexible; anal fin spines weak, 1-2 = Atherinidae (Atherina boyeri - Caspian Sea)
      First dorsal fin spines 4 and very strong; anal fin spines strong, 2-4 (usually 3) = Mugilidae (Caspian Sea, Marine)

18. Anal fin spines three or more; first dorsal fin spines rarely 11, usually 10 = Centrarchidae (Namak Lake)
      Anal fin spines one or two; first dorsal fin spines 13 or more = Percidae (Caspian Sea)

19. Three or more pairs of barbels present; no scales or scales minute ---> 20
      Barbels two pairs, one pair, or absent; scales present and well developed ---> 25

20. Four pairs of barbels present; nasal barbels present = Heteropneustidae (Heteropneustes fossilis - Tigris River)
      Three pairs of barbels present; no nasal barbels ? check this--->  21

21. A thoracic adhesive apparatus ("sucker") present on the belly between the pectoral fins formed from longitudinal skin folds = Sisoridae (Tigris River, Gulf)
      No sucker ---> 22

22. Barbels longer than head; no scales; strong pectoral fin spine ---> 23
      Barbels shorter than head; scales minute or absent; no pectoral fin spine ---> 24

23. Dorsal fin spineless, small and short (3-4 rays) and spineless; anal fin elongate (> 69 rays) = Siluridae (Caspian Sea, Lake Orumiyeh, Tigris River)
      Dorsal fin with a strong spine, well-developed (7-8 rays); anal fin shorter (6-10 rays) = Bagridae (Mystus pelusius - Tigris River)

24.  = Cobitidae
= Balitoridae

25. Discrete, short adipose fin present = Salmonidae (Caspian Sea, Namak Lake, Lake Orumiyeh)
      No adipose fin ---> 26

26. Dorsal and anal fins long, dorsal with more than 30 rays; head snake-like ---> Channidae (Channa gachua - Hormuz)
      Dorsal and anal fins short, less than 20 rays; head normal ---> 27

27. No teeth in jaws; lateral line usually obvious ---> 28
      Teeth in jaws; no lateral line pores ---> 29

28. Adipose eyelid present; branchiostegal rays 4; alar scales on caudal fin (enlarged scales) = Chanidae (Chanos chanos - Hormuz)
      Adipose eyelid absent; branchiostegal rays 3; alar scales absent = Cyprinidae

29. Head naked dorsally; pelvic fins under dorsal fin = Clupeidae (Caspian Sea, Marine)
      Head covered with scales dorsally; pelvic fin bases not under dorsal fin ---> 30

30. Teeth conical; anal fin in males enlarged as a copulatory organ; females without sheath around anterior anal fin rays; body slender = Poeciliidae (Gambusia holbrooki)
      Teeth trifid; anal fin in males normal; females with a sheath around anterior anal fin rays; body robust = Cyprinodontidae

Brian W. Coad (www.briancoad.com)