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ECONOMIC IMPORTANCE OF FISHES

Published in Zoology
Tuesday, 13 June 2017 18:49
Fishes are very important to man economically.
 
  1. As food
  2. They give by-products
  3. To control diseases
 
1. FISHES AS FOOD
 
Fish is good food to man. The flesh of flesh is rich in proteins and fat. Dry fish also contains A and D vitamins. It contains minerals. Much of the flesh can be digested by man. Food fishes are both marine and fresh water.
 
Ex: Labeo, Catla, Trygon, etc
 
2. FISH BY-PRODUCT
 
Fish Oil: From the liver of the many fishes oil is extracted.
 
A. Cod liver oil: It is extracted from the cod fishes.
 
B. Shark liver oil: It is extracted from the liver of the shark. These oils contain A and D vitamins.
 
C. Bombay duck oil: The Extracted oil from Bombay duck is used in Paints.
 
Fish meal:  Many fishes are dressed and cooked. Then they are dried. Fishes are made into fine powder. This is called fish meal. It is used by weak and convalsent people.
 
Isinglass: It is a pure gelatin substance. it is obtained from air bladder of the fishes. it is used to clarify wines.
 
Fertilizers: The ‘fish waste’ materials have more calcium, protein, phosphorous and other substances. These materials are grined into powder. It is used as fertilizer to Grape gardens, Coffee and Tea plants.
 
3. CONTROLLING DISEASES
 
Some of the fishes like Gambusia barbus will eat the larval forms of mosquitoes. Thus they prevent the spread of malaria disease.

FRESH WATER FISHES IN AQUACULTURE

Published in Zoology
Tuesday, 13 June 2017 18:05
TYPES OF CULTURABLE FRESH WATER FISHES
 
India occupies second position in prawn culture and seventh position in fish culture and production.
 
Fresh water fishes cultured in India are (a) Major carps (b) Minor carps (c) Murrels (d) Cat fishes (e) Exotic fishes and (f) Cold water fishes.
 
MAJOR CARPS
 
Indian major carps grow fast and can reproduce even in artificial ponds. They feed upon phytoplankton, zooplankton, decaying organic matter, aquatic plants etc. Stomach is absent in the alimentary canal of major carps. Three types Of Indian major carps are cultured in fresh water ponds.
 
1. Catla catla:
 
This is commonly called catla. It is the largest carp with grayish colour above and silvery on sides. It grows to about one meter. It has broad and stout body, broad head with upturned mouth, prominent lips and elongated fins. The dorsal side of the body is more concave than ventral side. It occurs in surface water. It matures by second year. slender fish. Body is silvery but dark gray along its back.
 
Pectoral, ventral and anal fins are with orange tinge. It grows to about 65 cms. The fish has a small head with a blunt snout. Mouth is sub terminal, caudal fin is sharply forked. This carp is also used in culture fishery. It normally occurs in bottom waters of rivers and tanks.
 
3. Labeo rohita:
 
This fish is commonly called rohu. It has an elongated body.    Head is small but it is with a prominent terminal mouth, thick lips with short barbels. Colour is bluish or brownish gray above. Scales are gray and red or black. It grows to about 90 cms. This carp occurs in column waters of all rivers and canals. The above major carps are extensively cultured in fresh water ponds and lakes of India.
 
MINOR CARP FISHES
 
The minor carp fishes grow to a size of 30- 100cm. with an average weight of 1 to 1.5 kg. Rate of egg production is very low in these fishes.
 
1. Labeo calbasu:
 
It is commonly found in fresh water ponds and tanks of India. The body is bluish green in colour with small head and folded lips. The snout consists of four black coloured long barbs. It is cultarable in ponds. It reaches to a size of 1 m and l .5 to 2 kg. in weight.
 
2. Labeo bata:
 
It is grown in compositefish culture along with other Indian major carps. It attains sexual maturity in 9 - 10 months.
 
3. Labeo fimbriatus:
 
It has folded lips and lives in deep water zone. It grows to a maximum size of 90 cm and 450 g. in weight. Red spots are present on the scales of middle row.
 
The other minor carp fishes are Labeo contius (pig mouthed fish), Cirrhinus cirosa (white carp) and puntius karnaticus.
 
MURREL FISHES
 
These are air breathing fishes with long cylindrical body, flattened head and protractile mouth. These can grow in fresh water ponds, irrigation canals, wells and marshy areas. They breed even before the onset fo monsoons.
 
1. Channa punctatus or Ophiocephalus: (Snake head)
 
It is a long fish with snake like body and accessory respiratory organs. As it lives outside the water also, it is commonly called Livefish. It is coloured differently. It grows to an average length of 30 - 35 cm. It is a common food fish of high demand.
 
2. Channa striatus: (stiped snake head)
 
The body is coloured dark brown with yellow bands on either side. The fish feeds on worms and insects and grows to a length of 0.9 mt. Its flesh is good for health as it does not contain cholesterol.
 
3. Channa marulius: (large headed snake fish)
 
It is also used for culture in fresh water ponds and tanks.
 
CAT FISHES
 
The cat fishes are predatory fishes. Their skin is devoid of scales. Two pairs of barbels are present on upper and lower jaw. Most of the fish body is utilized as food due to absence of scales and spines.
 
1. Clarias batracus:
 
It is commonly found in brackish and fresh water ponds of India, South and West Asian countries. Head is slightly compressed and enclosed by plates. Body is brown or dark gray in colour. It is not only used as food but also for experiments in laboratories. It is provided with Accessory respiratory organ. It grows to a size of 45 cm.
 
2. Heteropneustes fossilis:
 
The head is flat with laterally compressed body. It possesses accessory respiratory organs and lives in lake kolleru of A.P. It feeds on molluscans, algae and grows to a size of 45 cm.
 
3. Clarias macrocephalus:
 
It grows to a size of 40cm.
 
4. Anabas testudeneus: (Climbing perch)
 
It grows to a length of 15cm and feeds on aquatic insects. head is triangular with wide mouth and greenish in colour
 
5. Etropius suratensis:
 
It is commonly called pearl spot due to presence of transparent patches shining like pearls. The body is greenish, light pink and possesses eight black stripes. It is regarded as a good food fish due to delicious smell. It is not a predator, builds nests during the breeding season and hence regarded as most suitable for culture in ponds and lakes.
 
6. Wallago attu:
 
It is a cat fish found in all rivers and lakes of India. Head is larger than trunk. The body is laterally compressed. Tail is extraordinarily long and slender. It grows to a size of ito 2 mt. but captured at 90 cm. length. Two pairs of barbells are present on the head. Mouth is large with large jaws having teeth for feeding on fresh water. Hence it is called fresh water shark. As it is a predator fish, it is not suitable for artificial culture.
 
7. Mystus seenghala:
 
Four pairs of barbs, elongated upper jaw, long maxillary barbs, deeply divided caudal fin are the main features of the fish.

EXOTIC FISHES
 
When the indigenous fishnet are not favored for culture due to economic viability, exotic breeds are selected and cultured. These fishes yield nutritious food and earn foreign exchange.
 
1. Cyprinus carpio: (Common carp)
 
This fish was imported from China and introduced into Nilagiri lakes. The growth of the fish is higher and grows to a length of 75cm and 6.5 kg weight. It breeds thrice in a year. When cultured under extensive system, the productivity was at 1500 kg/ha.
 
2. Osphronemus goramy: (Gowramy)
 
It was imported from Jawa and Maritius and introduced into fresh waters of Madras and Calcutta. The rate of growth is very slow.
 
3. Ctenopharyngodon idella: (Grass carp)
 
It grows in fresh water, polluted water and brackish water of low salinity. It feeds on aquatic weeds and used to eliminate them. It is native of Japan and China and was introduced into Cuttack waters in 1959. It can grow to a size of 0.9m in size and 7kg in weight.
 
4. Hypothalamychthys molitrix: (silver fish)
 
It was imported from Hongkong and introduced into fresh water of Cuttack  region. The mouth is located dorsally at the tip of snout, the body is laterally compressed and enclosed by small shiny scales. It feeds on the left over food particles of carp fish and grows quickly. It reaches to a length of 60 cm and weighs about 1.5 kg.
 
5. Tilapia mossambicus
 
It was imported from East Africa in 1952. The upper jaw in males is larger. It breeds even at the age of two months.
 
COLD WATER FISHES
 
These fishes are commonly called sport fishes. These fishes include trouts and Mahseers.
 
1. Salmogiardneri: (Rain bow trout)
 
It is a north American fish introduced into rivers and lakes of Ooty and bill ranges of kerala. The dorsal and caudal fins are pinkish with dark spots. It grows to a length of 1 .8m. and weigh upto 100kg..
 
2. Tortor: (Mahseer)
 
Head possess short rosiral and long maxillary barbs. Dorsal ride of the body is grayish green, lateral sides are gold and belly is silvery white. Even though it is adapted to grow well in canals but now it is cultured in reservoirs like Bakranangal. It grows to a size of 1 mt. and considered as good food fish.
 
3. Tor Khudree:
 
Snout is pointed. Body dark coloured on dorsal and lateral sides while yellow on ventrolateral sides.
 
4. Tinca tinca (Doctor fish):
 
It is the native of Europe and West Siberia and was introduced in Indian waters. It grows to a size of 40cm.
 
BRACKISH WATER FISHES
 
The great estuaries on river mouths and backwaters offer important potential for fish culture of particulate species. The fishes generally reared in brackish water include some iidigenous fish like Mugil cephalus, Chanoschanos, Etroplussuratensis,Latescalcarifer and some exotic species like Tilapia mossambica, Osphronemus goramy etc.
 
1. Mugil Cephalus: (Gray mullet)
 
Although these fishes are available on the coastal region, they enter into brackish waters and rivers. The fish grows to a length of 90cm. It is also reared in ponds in kerala and Tamilnadu. 70% of the body is useful as food.
 
2. Chanos Chanos:
 
This is commonly known as milk fish. The dorsal side of the body is greenish and shiny. It is mostly obtained in kerala state. It is highly used in brackish water culture and highly preferred food fish.
 
3. Iates calcarifer:
 
It is commonly known as perch. It is found in sea water, brackish waters and also in large rivers. The dorsal side of the body is dark greenish while the ventral side is shiny, It grows to a size of 60cm and may reach to a size of 150cm. It is also highly preferred as food fish.
 
FISH HARBOURS OF PAKISTAN

The major fish harbours of Pakistan are:
 
  • Karachi Fisheries Harbour is being operated by Provincial Government of Sindh.
  • Karachi Fish Harbour handles about 90% of fish and seafood catch in Pakistan and 95% of fish and seafood exports from Pakistan.
  • Korangi Fish Harbour is being managed by Federal Ministry of Food, Agriculture and Livestock.
  • Pasni Fish Harbour being operated by Provincial Government of Balochistan.
  • Gwadar Fish Harbour being operated by Federal Ministry of Communication.


AQUA CULTURE (PISCI CULTURE)

Published in Zoology
Tuesday, 13 June 2017 13:03
1. CAPTURE FISHERY
 
Initially, man tried to capture fishes by using different types of gear in different water bodies. In this method, he is able to collect only the existing fish in waters. This method of capturing the naturally existing fish is termed as capture fishery Capture fishery is still the only method used in catching fist, in huge water masses (marine water and riverine water systems). In the year 1987 the capture fishery from marine water constitutes 1.65 million tonnes.
 
2. Culture Fishery
 
Man developed the idea of growing selected fish. For this purpose, the fishes such as carps breeding in flowing waters are collected. They are artificially induced to breed in confined water bodies. The pituitary gland extract is injected to the breeders. The breeders under the influence of pituitary hormones, breed in these waters. This method is called induced breeding. The fish hatchlings thus obtained are called fish seed.
 
While growing the fish seed, man is also able to control the environmental conditions. He is able to supply additional food for their growth. The diseases common for fishes are controlled. Due to this, better growth of fishes is achieved. Ultimately, he is also able to grow more number of fish and achieved better production of fish. This method of growing selected fish under controlled environmental conditions in confined water bodies so as to achieve maximum productivity is termed as culture fishery.
 
The culture fishery is also of two types viz.,
 
  1. Fin fish fishery
  2. Shell fish fishery.
 
The fishery concerned with fishes having fins is called fin fish fishery. The fishery concerned with fishes having shell is called shell fish fishery.
 
Molluscans, Crustaceans such as crabs, lobsters and prawns constitute shell fish fishery.
 
The culture of fin fishes is also termed as pisci culture. The culture of any aquatic food organisms can be referred to as aquaculture.
 
Pakistan has substantial areas of inland waters as a result of its location as the drainage basin for the Himalayas. The region between 33 o N and 20 o N consists of a network of rivers, canals, reservoirs, lakes, waterlogged areas and village ponds, etc. with a total area of about 8.6 million ha. Of this total, some 30000 ha correspond to the area utilized for cold-water trout production and other commercially important sport fishes such as mahseer (Tor tor) and snow trout (Schizothorax richardsonii). Also read Aquaculture in Pakistan.
 
The fish not only yields flesh but also vitamins like A and D. Due to less cholesterol content the fish flesh is used as food for heart.

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