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The per capita consumption of fish has been 3.2kg on an average up to 1992 as against estimated requirement of 11.0 kg pisciculture has the potentiality of popularity. Fish is rightly considered as the “Poor man’s diet”. It is almost zero carbohydrate food, good for diabetics and other such patients. Fish is a rich source of protein, vitamins and minerals. A special feature of fish flesh food is content of vitamin B12, which is almost absent in plant food and also a good source of calcium and vitamin A. Fish also contains polyunsaturated fatty acids which are known to provide protection against cardio-vascular diseases. This has got advantages over the other meat food.

Planktophagus fishes have higher protein contents then do fish with other feeding habits.

When flesh of fish is put to an analysis the following major components are observed.

• Fish cum-poultry farming.

• Fish cum-duck farming.

• Fish cum-pig farming.

• Fish cum-paddy farming.

A) Fish Cum-poultry farming

Inland fish culture in conjunction with poultry rearing is a compatible business and can provide a readymade fertilizer for fish pond. In a larger sense fish and poultry are mutually complementary the former provides fish meal a protein rich poultry feed and the later is droppings which acts as fertilizers for plankton production to serve as natural proteinous fish feed. Fish meal is recognized as perhaps the choicest poultry feed. In an integrated fish cum-poultry farm, birds have to be housed in deep litter of battery system in which the pen flora is covered with hay. The floor of the pen is covered with chapped straw dry leaves, hay broken up groundnut shells maize straw and saw dust. Each bird should have about 0.3 m² space to live on the deep litter flooring bird droppings falling on the litter react with the flooring organic material. The litter has to be periodically churned for aeration and maintenance of hygienic conditions.

The embryogenesis or embryonic development of a sexually reproducing multicellular animal is prefaced by the gametogenesis as ovum and sperms.

In some animals both kinds of gametes are produced by a single individual which is called monoecious or hermaphrodite.

But in majority of animals both kinds of gametes are produced by different individuals to an animal species are called dioecious.

The kind of sex cells as spermatozoa and ova; and those organs which are immediately concerned with their production i.e. male gonads called as testes and female gonads as ovaries form the primary sexual characters of each sex.

Besides these primary sexual characters the male and female sexes differ from each other in many somatic characters, which are called secondary sexual characters.

Such a phenomenon of morphological differentiation or specialization in secondary sexual characters between male and female individuals of a species is called sexual dimorphism. Sexes are generally separate in fishes and only a few species are hermaphrodite.

Fish are of great economic value for man. In addition to it is an important item of food and provides several important by – products also which are as :

1) Fish oil

The most important fish by product industry is fish oil which acts as a vehicle for fat soluble vitamins i.e. A, D, E and K, and source of essential faty acids.

The oil of fish is categorized into two main types as the fish liver oil and fish body oil.

The oil abstained from the whole body of fish is called as body oil and is poor in vitamin contents.

The oil abstained from the only liver of the fish is called as the liver oil, and is good quantity of vitamins.

The body oil is less valuable as compared to the liver of the fish.

Fishes are used by human beings in different forms from time immemorial millions of human beings suffer due to hunger and malnutrition and fishes from a rich source of food, which has following importance:

1) Fish is an excellent food for mankind is more easily perishable than cattle, sheep and chicken.

2) Fish flesh is easily digestible by child and man.

3) Fish flesh has very great nutritive and medicinal values.

4) Fish flesh contains proteins, bass, vitamins, waters and minerals.

5) All the essential required amino acids are present in the fish flesh.

6) Fish flesh contains proteins about 13-20 % and it is easily digestible and nutritional.

7) Fish flesh is highly perishable commodity constituted as 60-80 % water.

8) Fish flesh contains about 1-8 % fats or oils and it is more important value of fishes.

In order to obtain maximum yield of fish from a lake or reservoir, it is essential to culture fast growing compatible species of different feeding habits is called as composite fish culture.

Any one kind of species cannot utilize the variety of food available in the pond. For a complete utilization of cheap natural food, pond fishes of different age groups or of different species may be selected for stocking. A combination of several compatible species with complementary food habits would make better use of the food resources of the pond as well as ecological potentials of the pond.

When fishes of different age groups and different species are cultured in same pond called as composite fish farming or mixed farming or polyculture. This is based on the principle that compatible species do not harm each other instead they utilize in the most efficient manner, all available food supply of the pond for maximum production of fish yield. There is no competition between different species on the other land they may be beneficial effect on the growth of others.

• Type of Aquatic weeds

• Different control method

• Advantage and disadvantage of Aquatic weeds.

Aquatic weeds are those unwanted and undesirable plants, which reproduce and grow in fast in water bodies. They are more harmful them beneficial for fish culture. Excessive growth of aquatic vegetation prevents effective utilisation of water and reduces productivity because they utilize the nutrients and also prevent the sunlight to read the deep part of the water body. This excessive growth restrict the living space of fishes, resulting into less production. The decay mass of these pollute weeds prevent the growth of more useful microorganisms. And disturb the food web and food chain and equilibrium of physico-chemical qualities of water. Liberation of toxic substance and waste decomposition of water body is most effective so it is necessary to identify and control them. It has the primary problem of management of Inland fishery cultures.

Aquatic plants grow on extremely wet soil and where water is available to plants in abundance such as ponds lanes river banks etc. or those plants which grows and found in the nearby water body or in water body. These plants are called as aquatic weeds because these are not attend the larger size and act as the weeds which is found in water so these are called as aquatic weeds.

Shallow weed infected ponds, swamps, marshes, pools. Bogs infected all inland water bodies. These infected inland water bodies provides shelter food and suitable environmental condition to grow and multiply to different pathogens and microorganism and macro-organism such as mosquitoes, snails other hosts.

Mosquitoes are the vectors of several diseases and carry parasites of malaria, filarial, yellow fever and so on the breed in all sorts of stagnant water and shallow weed infested ponds, swamps, pits gutters and all other kinds of inland water bodies. Different species of mosquitoes prefer different kinds of water for breeding purpose.

A number of fishes have little food value but are of immense utility to public health because of their larvivorous feeding habits. Fish is a natural enemy of mosquito eggs and larvae and its use as means of biological control has been recognized since olden times. Several species of fresh water fishes are known to be larvicidal and of use in the control of mosquito population. Biological control of this type is now regarded as one of the most potent tool in destroying the mosquito population without any causing harmful effect in the food chain and the human system. Man learnt to use them as one of his several measures to combat a number of serious diseases which are spread through the agency of insects. A number of larvicidal fishes directly feed upon mosquito larvae and thus their introduction in such water bodies where mosquitoes breed results in a very effective control on the population the mosquitoes in selection of the larvicidal fishes for such a control of diseases.

The oceans covering nearly 71% of earth surface are classified into several zones. There are different zones such as neritic zone, oceanic zone. Neritic zone consists of different zones. Which are present in bank side of ocean. The oceanic zone forms two major zones as pelagic and the benthic zones. In the pelagic zone the organisms float or swim freely on the surface and in the benthic zone they associations are widely different and there is no light, water is called dark zone water or aphotic this constitute the deep sea fishes which found in the bottom of the sea the region between 200-1000 meters is called as the mesopelagic zone. The part of the ocean below 1000 meters is called bathypelagic zone and the deepest part of the deepwater is called benthic zone. Mesopelagic, bathypelagic and benthic zone constitute the deep sea water. A large number of species of fish in habits the deep sea. Fishes living in the deep water of the oceans are exposed to more or less uniform conditions of life and they are adapted differently.

• Source of colour

• Colour changes in fishes

• Regulation of colour changes

• Significance of colour changes.

The coloration is most well-marked in fishes A large number of fishes are brightly and brilliantly coloured and others are of more uniform and sober shade. On fish body characteristics markings in the form of base strips, spots and blotches etc. coloration is mainly due the skin pigments but the back-ground colour may also be due to the underlying tissues and body fluids. Coloration relates to the life style of the fishes and the patterns so produced have functional significance.

Generally the fishes are darker on their upper surfaces this is because their upper surfaces being exposed to sun light undergo pigmentation, while ventral surface with gradual shading on the sides. Some fish species like the gold fish, carassius exhibit almost uniformly bright colour all over the body. Cave fishes living in total darkness have lost the pigments and grown colourless. Several species of the genera synodontis living in the river of Africa swim in inverted position and so the pigmentation is reversed in them.

• Structure and working of electric organs in- Electric eel, electric catfish, electric ray.

• Mechanism of electric discharge formation and control of electric organs.

Fishes possess a number of adaptive structures which have been evolved to meet special requirements faced by them. The electric organs are highly specialized structures that enable their possessors to produce store of discharge to electric current. Fishes are unique in the animal kingdom in being capable of generating an electric current.

About 250 species of both, the cartilaginous and bony fishes of fresh and marine waters are known to possess the electric organs. Most of these restrict to the tropical fresh water of Africa and South America. Many species of rays, skates, and the eels are known to possess small electric organs that give a weak discharge. These fishes can produce electric field outside the body. Electric fishes have been divided into two types-strongly electric and weakly electric, depending on the strength of the current.

In fishes the outermost covering of the body is called as exoskeleton. The exoskeleton is covered by the covering called as skin. In most of the fishes the skin is covered with an exoskeleton in the form of scales, but a few fishes are naked having no scales on the body and body is covered only by thick skin as like the catfishes. While some other fishes like the polyodan and the Acipenser exhibit an intermediate condition, having scales or scale like plates only at same localized regions of the body. The scales of fishes are products of the activity of the skin. The scales of fishes have become modified in various ways mainly to provide protection.

The scales are useful for the classification and identification of fishes (in fish Taxonomy it is used) Fish scales are self for the determination of age of the fish. Scales are also useful for the estimation of the number of the spawning.

Scale provide important information about extinct fishes and useful in identifying food habits of piscivorous animals. Scales are important exoskeleton in fishes According to the mode of origin there are two types of scales i.e. 1) Placoid and 2) Non- placoid scales.

The animals, which are aquatic cold blooded respires with the help of gills and swim with the help of fins such animals are called as fishes. Fishes have various body forms according to the environment and in changing the life of fish the body form of fish are found. The fish swim in water with the help of fins. The fins are present on all body of the fish. In swimming the body form is also important. Following are the various body forms found in fishes.

Body Forms

Following are some of the body forms in fishes:

1. Anguilliform body from:- When in fishes the body form is the anguilliform shape and size, like that of eel or anguilla type, then such body form is called as angilliform body form.

2. Depressiform body form :- When in the fishes body form is flattened from above downwards, means the body form is depressed dorso-ventrally it is called as depressiform body forms like that of angler fish, ray fish is also called dorso-ventrally depressed.

3. Disciform body form :- When in fishes the body form is flattened form sides or the fish is laterally compressed on both sides that type is called as disciform body form of laterally compressed body form like that of flat fishes.

This group includes a large number of bony fishes in which the primary upper and lower jaws are supplemented by the addition of membrane bones which forms secondary jaws. Hence they are called as teleostomi or perfect mouthed fishes.

All major groups of fresh water fishes lived successfully and flourished during the Devonian period which is also called as the “Age of fishes”. Teleostomii are characterized by a unique mechanism of opening the mouth by lowering the mandible through hyoid apparatus, therefore the skull is hyostylic or the amphistylic. Presence of an ossified operculum, an interhyal bone and the branchiostegal rays are the diagnostic features of this group.

The evolutionary classification based largely on the typological methods has been adopted a number of fish taxonomist. Foremost among them are Gunther and Cope (1871) Boutenger (1904); Jordan (1923); Regan (1929); Berg (1940) and Romer (1959). Out of the various schemes proposed by aforesaid taxonomists, there is no agreement among the ichthyologists regarding the classification of fishes. Fishes constitute more than one half of all vertebrates comprising around 40,000 species.

The classification of Berg (1940) is most widely accepted, it is based upon the conclusions of Jordan (1923) and Regan (1929). Many ichthyologists consider Bergs classification as a minor revision. Berg scrutinizing the merits of the other classification proposals and make advanced classification, which is accepted all over the world.

What are Chordates?

The animal kingdom is divided first into several major animal groups called phyla: singular phylum. There are approximately so animal phyla. The last major groups of the animal kingdom are known as phylum chordate it was created by Belfour, in 1880. The name of this phylum is derived from two Greek words, the chorda- meaning a string or cord and ata- meaning bearing. The reference is to a common characteristic feature in the form to a stiff, supporting rod – like structure along the back, the notochord (Gr – noton – back, L-chorda-cord). This is found in all the members of the phylum at some stage of their lives. Chordates are animals having a cord are “notochord” or “Invertebrates” since they have no notochord or back bone in their body structure.

Phylum chordate is the largest to the deuterostiome phyla. It is the highest and the most important phylum comprising a vast variety of living and extinct animals including man himself most of the living chordates are the well known familiar vertebrate animals, such as the fishes, amphibians, Reptiles, birds and mammals.

Three fundamental characters of chordates:-All the chordates possesses three outstanding unique characteristics at same stage in their life history. These three fundamental morphological include,

A fish is defined as the cold blooded vertebrates, which catch with the help of gills and swims with the help of fins and which are aquatic in nature. In broader sense the term fishery is used for the rearing and management of all aquatic animals which are useful to human being e.g. fishes, crustaceans and mollusks. The term fishery science is related to the rearing and management of fish on large scale by proper utilization of available water sources.

Fishes comprise of about 33100 species (FishBase 2015) differing widely from each other in shape, size, habits and habitats. Some of them are very small or more than an inch in length, while a few attain a length up to 18.50 m. they live in all free flowing rivers, lake, canals, dams and in almost every place where there is water.

Fishes usually have a stream lined body but some are elongated snake like and a few are dorso-ventrally compressed. They have paired and unpaired fins supported by soft or spiny fin rays. Dorsal, caudal and the anal fins are unpaired while the pectorals and pelvic (ventral) are paired fins. A number of species possess barbless which are excellent organs of touch.

Introduction

The economic choice of any process is the criterion for efficient utilization of the by-product that is produced along side of main product. During manufacture of major dairy products, the dairy industry also ends up in producing different by-products. Various by-products of dairy industry are skim milk, butter milk , whey and ghee residue. Dairy industry is particularly confronted with the problem of economic utilization of whey and ghee residue. The techno-economical problems associated with utilization of these by-products, is now receiving considerable attention. More efficient, cost effective and sophisticated technologies have opened up new vistas for manufacture of number of derived by-products. Further more the market for dairy by-products, as an ingredients in other consumer food products like snacks, ready meals and microwavable food products, has been growing.

Introduction

In the recent past there has been a great deal of questioning regarding role of milk fat in cholesterol metabolism and other body functions. The enormous wave against cholesterol containing foods has damaged the image and market growth of fat rich dairy products. This trend is due to presence of saturated fats and cholesterol that are known to increase the incidence of coronary heart diseases one of the common cause of heart attack. The educated and urban society is more health conscious about the presence of cholesterol in their diets. This has led to the greater demand of cholesterol free foods. Ghee being a saturated fat and containing little amount of cholesterol, is suspected to contribute towards coronary heart diseases. However, critically surveyed scientific literature indicates that there is no evidence of any association of milk fat with increased risk of coronary heart diseases. Age old and proven Ayurvedic system of medicine has proved the usage of ghee to induce several beneficial effects on human health and used extensively for therapeutic purpose like in treatment of skin allergy, respiratory diseases, curative for ulcers and eye diseases. This suggest that ghee is a valuable form of dietary fat.

Introduction
Ghee is the pure clarified butter fat prepared chiefly from cream and/or desi butter (Makhan) to which no colouring matter is added.  Ghee manufacture has great significance and relevance to Indian masses and the dairy industry. Ghee is a very popular product since ancient time and has greater demand during festival and other ceremonial functions where use of ghee in food has been considered to delicacy due to its pleasing flavour and aroma. There are sufficient recorded evidence to prove that the manufacture of ghee originated from India and has been used extensively for religious and dietary purposes since Vedic times. Presently about 28% of total milk production is utilized for manufacture of about 1 million tones of ghee per annum. It is the traditional product with an established market. Cow ghee is golden yellow in colour, and is attributed unique therapeutic value.  The colour of buffalo ghee is greenish yellow due to presence of pigments called billirubin and billiverdin. Ghee is characterized by its pleasant, cooked and rich flavour. The preferred texture is of larger uniform size from grains having non-greasy consistency.