• Fish is nutritionally very rich.
  • Fish is a rich source of protein, essential oils and minerals.
  • The approximate composition of fish is:


  1. Moisture 40 – 90%
  2. Protein 06 – 19%
  3. Oil 01 – 64%
  4. Ash 0.4 – 1.5%


  • Generally fish lay eggs and the fertilization is external.
  • In some cases the fish may give birth directly to living young.
  • In some sharks, the embryo is completely developed internally (internal fertilization) and the female gives birth to fully developed young one.
  • Usually fish lay a very large number of eggs, as they do not exhibit parental care.


·         Based on feeding habits, the fish can be grouped into
1.       Herbivorous (sardines and grass carp)
2.       Carnivorous (sharks and barracuda)
3.       Omnivorous (catla)
4.       Detritivorous ( carp and tilapia)

·         Most of the fish migrate either for feeding or breeding. Two most important migrations’ are
1.       Anadromous are those which migrate upstream for spawning. Eg. Salmon and shad
2.       Catadramous are those which migrate from upstream to brackish water. Eg. Eels, fresh water prawns.

·         Fishare broadly classified as
1)      FIN FISH: They are verte brates. They are further subdivided into
a)      LEAN FISH:  are mainly flat, contains oil, only in the liver. They are mostly deep sea fish. Ex. Pomfret, Sole, Turbot etc.
b)      OILY FISH: are mainly round and contain fat all over the body. Fat varies from 1.5 % – 20% in different varieties. These are more colourful and move towards the surface. Ex. Mackerels, sardines, carp, rohu, trout masheer etc.
2)      SHELL FISH:  have a shell covering the body. They are invertebrates. They are further subdivided into
a.       MOLLUSCS: their body is enclosed inside the shell. The shells increase at the rate of one ring per year to allow for the growth of the fish. The age of the mollusk therefore can be roughly estimated by the number of rings on the shell. Mollusk are of two types-
¨       UNIVALVES: body is inside one whole shell. Eg. Whelks and Whinkles.
¨       BIVALVES: have two distinctly separate shells joined by a hinge – like membrane. The movements of the shell are controlled by a strong muscle. When the muscle relaxes, the two halves of the shell fall open. Eg. Oysters, scallops, mussels, clams, cockles etc.

b.       CRUSTACEANS:  these have a segmented, crust like shell. Ex. Lobsters, crabs, prawns, shrimps. The shells of crustaceans do not grow with the fish, but are shed each year, with a new one grow with the fish, but are shed each year, with a new one forming to suit their new size.
·         Eyes should be bright, not sunken.
·         Grills should be red.
·         Tail should be stiff.
·         Flesh should be firm and not flabby.
·         The scales if any should be plentiful.
·         There should be no unpleasant odour  (ammonia gas).
·         To test a cut piece, press down with the finger, and if an impression is left, then the fish is stale.
·         Fish should natural covering of mucous on the body.
·         Should appear heavy in accordance to the size. Light fish shows signs of de – hydration.
·         Always try to purchase fish without any wounds or bruises.

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