Economic importance of fish

a) Fishes as Food:

• Fish diet provides proteins, fat and vitamins A and D.
• They have a good taste and are easily digestible.
• They are also preserved by smoking, salting and freezing in ice.
• Refrigeration and quick freezing is a good method of preserving the fish for future consumption.
• The flesh of fish is rich in proteins and fat. It contains vitamins A and D and minerals.

b) Fish By-Products:

• Liver oil contains vitamins A and D, while the body oil contains them in traces only.
• The refined oil from the liver of fishes has a medicinal use, being the source of vitamins A and D.
• The body oil from fish has many uses, such as painting, varnishing, soap, candle, leather and steel industries.
• Liver oil contains 55-75% fat, 5-10% protein and the rest water, and is of considerable medicinal value.
• Fish Body oil is used in manufacture of paints & Varnishes, cheap soaps.
• Use in dressing of leather & tanning of skin,
• Use in manufacture of lubricants & candle,
• Use in steel and iron industry,
• Use in manufacture of printing of inks and plastics,
• Use for smearing the surface of boats for longer preservation.

c) Fish as food for livestock:

• Fish used as artificial food for poultry, pig and cattle.
• The cooked material of fish is pressed to remove moisture and dried in the sun at suitable platforms. Such a dried fish product is called “fish meal” and is a highly nutritive product that makes an excellent feed for poultry, pig and cattle.
• Fish meal contains 55-70% protein, 2-15% oil/fat and 10-20% minerals.

d) Fish Manure and Guano:

• The head, tail and body covering is used to prepare proven manure and contains about 6% nitrogen and 3.4% phosphate with an appreciable amount of lime.
• These residues are sun dried, ground and are converted into manure, which contains a high percentage of nitrogen and phosphate.

e) Fish Glue and Isinglass:

• Liquid glue is prepared from the connective tissue as an adhesive for paper, wood, leather and glass.
• The air bladder of fishes is used for preparing isinglass, which is a shining powder and is used for clearing wine, beer, making edible jelly and in the preparation of adhesive material.

f) Fish Leather:

• The skin of several fishes like the sharks and rays are used for making polishing and smoothing material.
• The dried and treated skin is also used for preparing ladies shoes, money bags, suitcases, belts etc.

g) Fish Fin:

• The fins of sharks are exported to china where they are used for preparing soup.

h) Biological control (To control disease)

• Many species of fishes are larvivorous in habit and prey upon insect larvae, for example Puntius sp., Oxygaster sp., Barilius sp., Danio sp., Colisa sp., Rasbora sp., Esomus sp. etc.
• Larvivores fishes feed upon larval phase of parasitic pathogens and help to control successfully the population of mosquitoes too.
• Some of the fishes like Gambusia barbus will eat the larval forms of mosquitoes. Thus, they prevent the spread of malaria disease.

i) Recreational Value:

• Fishing forms an important out door game for millions of people. In Nepal, sportsmen catch various species of Schizothorax, Tor tor, Bagarius bagarius, Catla and other carps.

k) Industrial value:

• Many people are involved in marketing or engaged in subsidiary industries such as refrigeration, preservation, canning, and in the manufacture of fish products and by products.

l) Decorative Value:

• Many species of beautifully coloured fishes are kept in aquaria, ponds and lakes and used for ornamentation.
• Juvenile fishes are maintained by stockists who offer several varieties for this purpose and earn their livelihood from this trade.

m) Other Uses of fishes:

Fish also used to make food items like fish macaroni, fish sauce, fish biscuits etc.