Fish Biodiversity And Stocking Density


Fish are cold-blooded animals, typically with backbones, gills, and fins (rather than pentadactyl limbs), and are primarily dependent on water as a medium in which to live. Different kinds of fish are found in freshwater,brackish water and  Marine water  such as Carp fish,cat fish, perch fish,snake head and ell fish etc.

  1. Carp Fish

Carp are various species of oily freshwater  fish from the family  Cyprinidae, a very large group of fish native toEurope to Asia. Introductions in many countries have helped to make carp the most widely distributed freshwater fish in the world. They are extensively farmed in Europe, Asia and the Middle East, and are a popular angling fish in Europe.

  • General Characteristics of Carp Fish :
  • The colour of carp varies. In the wild they are usually olive green to bronze or silvery in colour with a paler underside .They show a much broader range of colours and colour patterns,with various combinations of white ,black,red,yellow,blue and orange markings
  • Body stout , slightly compressed
  • Head moderate ,triangular ; snout obtusely rounded
  • Scale variations , including large shiny scales either scattered or in a line along the flanks (Mirror carp) or an absence of scales (leather carp) are also common in ornamental and wild fish
  • Carp are omnivorous, and their diet varies depending on what is available


  • Indigenous Species: Indigenous fish are native species which are not imported. Having no barrier of geographical conditions to move. Well adjustment with the environment. Ex: Labeo rohita


  • Exotic Species: Species, which are introduced from the foreign countries for commercial purpose is known as exotic species . E.g. Silver carp , grass carp etc.




  • List of Indegenous and Exotic Carp Fish

( Indian Major carp / Indegenous Species )



Local Name


Common Name Scientific Name  













Labeo rohita











Catla catla






Mrigal Carp






Cirrhinus cirrhosus








Orange-fin labeo




      Labeo calbasu


Exotic Fish



Grass carp



Grass carp



Ctenopharyngodon idella



Silver carp



Silver carpp



Hypophthalmichthys molitrix



Mirror carp



Mirror carp


Cyprinus specularis


Black carp



Black Chinese roach



Mylopharyngodon piceus


Bighead  carp


Bighead carp

Hypophthalmichthys nobilis


Common carp



Common carp



Cyprinus carpio



  1. Catfish

Catfish (or catfishes; order Siluriformes or Nematognathi) are a diverse group of ray-finned fish. Named for their prominent barbels, which resemble a cat‘s whiskers, catfish range in size and behavior from the three largest species, the Mekong giant catfish from Southeast Asia, the wels catfish of Eurasia and the Piraíba of South America.

3.1. General Characteristics of Catfish:

  • Many catfish are nocturnal
  • Most catfish are bottom feeders.
  • Catfish have a variety of body shapes, though most have a cylindrical body with a flattened ventrum to allow for benthic feeding
  • Catfish may have up to four pairs of barbels: nasal, maxillary (on each side of mouth), and two pairs of chin barbels, even though pairs of barbels may be absent depending on the species.
  • Catfish have no scales; their bodies are often naked. In some species, the mucus-covered skin is used in cutaneous respiration, where the fish breathes through its skin. In some catfish, the skin is covered in bony plates called scutes; some form of body armor appears in various ways within the order


  • List of some culturable catfish of Bangladesh :
Indegenous Culturable Cat Fish
SL. Local Name


Common Name Scientific Name Image





Striped dwarf catfish



Mystus vittatus



Nuna tengra



Long whiskers catfish




Mystus gulio



Gulsha tengra



Gangetic mystus


Mystus cavasius





Long Whiskered catfish



Sperata aor






Walking catfish


Clarias batrachus









Wallago attu






Stinging catfish



Heteropneustus fossilis







Pabda Catfish



Ompok pabda



Kani pabda



Butter Catfish/

Pabda catfish



Ompok bimaculatus




Yellowtail catfish


Pangasius pangasius

Exotic Culturable Cat Fish

Thai pangus


Sutchi catfish



Pangasius hypophthalmus


African magur


North African Catfish


Clarius gariepinus


  1. Perch fish

 Perch is a common name for fish of the genus Perca, freshwater gamefish belonging to the family Percidae. The perch, of which there are three species in different geographical areas, lend their name to a large order of vertebrates: the Perciformes, from the Greek perke, simply meaning perch, and the Latin forma meaning shape. Many species of freshwater gamefish more or less resemble perch, but belong to different genera.

4.1. General Characteristics of Perch Fish

  • The general body type of a perch is somewhat long and rounded.
  • True perch have “rough” or ctenoid
  • On the anterior side of the head are the maxilla and lower mandible for the mouth, a pair of nostrils, and two lidless eyes. On the posterior sides are the opercula, which protect the gills, and the lateral line system, which is sensitive to vibrations in the water.
  • They have paired pectoral and pelvic fins, and two dorsal fins, the first one spiny and the second soft. These two fins can be separate or joined.
  • Perch are carnivorous fish most commonly found in small ponds, lakes, streams, or rivers.
  • Perch are popular sport fish species.
    • List of Some perch fish:
SL. Local Name Common Name Scientific Name Image





Climbing perch


Anabus testudenius



Banded gourami  


Colisa faciatus


Lal khalisa



Dwarf gourami



Colisa lalia


Chuna Kholisa


Honey gourami




Trichogaster chuna









Lates calcarifer



Napit koi



Mud perch



Badis badis






Gangetic leaffish



Nandus nandus






Frail gourami



Ctenops nobilis


Koi Bandi



Palmyra-fibre fish


Pseudosphoromens cupanus


Samudra koi


Atlantic tripletail




Lobotes surinamensis




  1. Snakehead Fish

The snakeheads are members of the freshwater perciform fish family Channidae, native to parts of Africa and Asia. These elongated, predatory fish are distinguished by their long dorsal fins, large mouths, and shiny teeth. They breathe air with gills, which allows them to migrate short distances over land. They have suprabranchial organs developing when they grow older, which is a primitive form of a labyrinth organ. The two extant genera are Channa in Asia and Parachanna in Africa, consisting of about 35 species.

  • General Characteristics of Snakehead Fish
  • Snakeheads are thrust-feeders that consume plankton, aquatic insects, and mollusks when small.
  • Snakeheads can become invasive species and cause ecological damage because in many areas to which they are not native the absence of natural enemies gives them top-level predator
  • Not only can they breathe air, but they can also survive on land for up to four days, provided they are wet, and are known to migrate up to 400 metres (1/4 mile) on wet land to other bodies of water by wriggling with their body and fins.
  • National Geographic has referred to snakeheads as “Fishzilla
    • List of Some Snakehead fish :
SL. Local Name Scientific Name Stocking Density






Spotted snakehead





Channa punctata






Snakehead murrel



Channa striata






Walking snakehead



Channa orientalis




Great snakehead



Channa marulius




  1. Eel Fish

An eel is any fish belonging to the order Anguilliformes (/æŋˌɡwɪlᵻˈfɔːrmiːz/), which consists of four suborders, 20 families, 111 genera and about 800 species. Most eels are predators. The term “eel” (originally referring to the European eel) is also used for some other similarly shaped fish, such as electric eels and spiny eels, but these are not members of the Anguilliformes order.

  • General Characteristics of Eel Fish :
  • Eels are elongated fish, ranging in length from 5 cm (2.0 in) in the one-jawed eel (Monognathus ahlstromi) to 4 m (13 ft) in the slender giant moray.
  • They possess no pelvic fins, and many species also lack pectoral fins.
  • The dorsal and anal fins are fused with the caudal fin, forming a single ribbon running along much of the length of the animal.
  • Eels swim by generating body waves which travel the length of their bodies. They can swim backwards by reversing the direction of the wave.
  • Most eels live in the shallow waters of the ocean and burrow into sand, mud, or amongst rocks.
  • A majority of eel species are nocturnal, thus are rarely seen.



  • List of Some eel Fish :
SL. Local Name Common Name  

Scientific Name




Tara baim


Lesser spiny eel


Macrognathus aculeatus


Shal baim


Zig-zag eel



Mastacemblus armatus


Guchi baim


Spiny eel


Mastacembelus puncalus






Monoptereus cuchia





Indian mottled eel



Anguilla benglensis





  1. Other Exotic Fish :

7.1. GIFT Tilapia : This kind of tilapia are prepared by genetic improvement through selective breeding. Genetic improvement of Farmed Tilapia ( GIFT ) to develop a faster-growing strain of Nile Tilapia  ( Oreochromis niloticus ) that was suitable for biioth small-scale and commercial aquaculture. ( worldfishcentre )

7.2.Monosex Tilapia : Tilapias tend to be prolific fishes and their fry often have  a high survival rate. This means that if we raise tilapia in a pond and allow them to reproduce freely, the pond will soon be filled with various size of tilapia- all competing with each other for food and space. This is not beneficial for any of them and will usually lead to decreased growth rate and stunted specimens.

In the wild the problem would normally be solved by predators filling their bellies with tilapia but farming ponds are often devoid of predators. One alternative is of course to introduce predators of a suitable size that will feast on juveniles while leaving the precious adult fish alone. Another solution is not to keep males and females together, i.e. to raise mono-sex tilapia.

When a farmer has to choose between male and female tilapia the most common choice is male tilapia since males grow faster and bigger than females. Male-only batches can be obtained through three main methods: hybridization, manual sexing, or hormones.

  • Mono-sex tilapia through hybridization : When certain tilapia species or strains mate with each other virtually all of their fry become male. When females do occur they are usually the result of foreign genetic material being present in one or both parent fishes due to earlier hybridization. If you need an all-male batch for your fish farm you can for instance contact a breeder that mates female Nile tilapia (Oreochromis nilotica) with male Blue tilapias ( aurea) or male Zanzibar tilapias (O. hornorum). Crossing males of the species O. aurea or O. hornorum with females of the species O. mossambicus (Mozambique tilapia) is another popular alternative.
  • Mono-sex tilapia through manual sexing : Manually sexing tilapia is difficult but not impossible. It is however very labour-intensive and therefore costly.
  • Mono-sex tilapia through hormone treatment : By subjecting young female tilapias to hormones, it is possible to turn them into males. Before opt for this method it is important to check any legislation pertaining to your area because the use of hormones in fish farms are restricted or even banned in certain parts of the world. Also check the market situation; you don’t want to find out too late that the consumer segment you’re aiming for dislike hormone treated food.


7.3. Hormone sex reversal of BFRI GIFT strain :

  • All male tilapia production ( 98-100 % ) technique
  • Male has 25 % higher growth rate than female
  • More than 90 commercial hatcheries have been producing >150 coreof monosex seeds adopting BFRI technologists
  • Improved tilapia seed and grow-out technique

7.4. List of GIFT tilapia :

SL. Local Name Common Name Scientific name Image





Oreochromis mossambicus







Oreochromis niloticus




  1. Stocking Density : Stocking density is the weight of fish kept in a given volume of water. Research and practical experience has showen that, on its own, stocking density is not necessarily one of the most important things affecting fish  Some fish seen to prefer lower stocking densities. Stocking densities that are too low can cause certain species of fish to become  territorial and aggressive towards each other.

Stocking density of a fish species in a pond varies by influence of  some factors ,these are

  • Culture technique ( Monoculture, polyculture,Integrated culture )
  • Culture Method ( Extensive, Semi-intensive,Intensive )
  • Size of fry
  • Size of pond
  • Depth of pond
  • Types of culture Environment ( Pond, lake, river etc)
  • Soli type
  • Culture time
  • Stocking density varies from area to area
  • Available of Natural food
    • Stocking density for Polyculture ( Carp fish and Chingri ) :
Number of Fry per Bigha ( 33 dec / 0.12 ha)

Carp fry size 10-15 cm and Galda chingri size 4-6 cm

Species When carp fish Major Species When Chingri major Species
Local Name Scientific Name
Sliver Carp Hypophthalmichthys molitrix 250-275 150-200
Katol Catla catla 125-150 75-100
Rui Labeo rohita 225-250  _
Grass carp Ctenopharyngodon idella 5-7   _
Galda chingri Macrobrachium rosenbergii 1000-1300 3000-6000


( Reff : Carp jatiya macher protipalon, DOF )

  • Stocking density of different species for Monoculture
  Treatment-1 Teatment-2 Treatment-3
Species Number of fry per Decimal Average Weight of fry

(g )

Number of fry per Decimal Average Weight of fry

(g )

Number of fry per Decimal Average Weight of fry

(g )

Tilapia 150 5 250 5
Shorpunti 85 25 125 25 175 25
Pangas 100 20 150 20 200 20
Thai koi 500 5 1000 5 2000 5
Shing 500 2.5 1000 2.5 1500 2.5
Magur 300 5 400 5 500 5
Galda chingri 125 5 150 5 200 5
Baghda chingri 125 5 150 5 200 5

( Reff : Salpo Meyader Nirapod Mach Chas , DOF , Page : 21 )

  • Stocking Density of Wait fry in Pond
Stocking Density of wait fry per decimal
Species Treatment -1

Number of Fry

Treatment – 2

Number of Fry

Catla 150-200 _
Silver carp 200-250 175-200
Bighead carp _ 150-200
Rui 150-200 100-150
Mrigal 100-125 150-200
Carpio 100-125 150-150
Grass carp 100-100 75-100
Total 800                   800-1000

( Reff : Carp jatiya macher pona protipalin , page 20 ,DOF )

  • On the basis of Food availability , Stocking density of Fish.
Species Number of fish per Hectare Percentage
Catla 500 10%
Silver carp 1500 30%
Grass carp 500 10%
Rui 1250 25%
Mrigal 500 10%
Common Carp 750 15%
Total 5000 100%

( Reff : Beel and Baor Matsya unnoion and Management Poster  , Bosot barite mach chas ,Page 156 )


  1. Conclusion

Stocking density is the moist important factor for aquaculture to get high production. Acquiring knowledge about Stocking density is must as a FMRT Student. By knowing proper knowledge about stocking density of fish , we can increase or fish production.


Written By: M Hasan Hridoy

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