In this article we will discuss about Integrated Fish Farming:- 1. Basic Principles of Integrated Fish Farming 2. Types of Integrated Fish Farming 3. Advantages 4. Disadvantages.
Basic Principles of Integrated Fish Farming:
Integrated fish farming is based on the concept that ‘there is no waste’, and waste is only a misplaced resource which can become a valuable material for another product (FAO, 1977). In integrated farming, the basic principles involve the utilisation of the synergetic effects of inter-related farm activities and the conservation, including the full utilisation of farm wastes.
It is assumed that all the constituents of the system would benefit from such a combination. However, in most cases, the main beneficiary is the fishes which utilises the animal and agricultural wastes directly or indirectly as food. As integrated farming involves the recycling of wastes, it has been considered an economic and efficient means of environmental management.
Rice fields which are water-logged for 3-8 months in a year, there is always small population of fishes that gain access to such waters. This probably had given rise to the practice of deliberate stocking of fishes and harvesting. The trapping of prawns and fishes with the help of ‘gamcha or dhoti’ in fallow paddy-fields has been an age old practice in India.
The culture of fishes in paddy-fields has been an off-season occupation for farmers:
(a) Objectives of Paddy-Field Aquaculture:
The objectives or advantages of paddy-field aquaculture are as follows:
(1) Paddy-field aquaculture provides additional income to the farmers.
(2) In areas where rice and fish form the staple food, paddy-field aquaculture makes available an essential diet for the people.
(3) As paddy and fish can be grown either simultaneously or alternately in the same water mass, it requires very little extra input by way of additional costs, particularly in management and labour.
(4) It provides off-season employment to the farmers and farm labours.
(5) Combination of paddy and fish farming is mutually beneficial. Fish cultivation promotes better paddy production by way of exercising an effective control on unwanted weeds, molluscs, noxious insects and their larval stages.
(b) Fishes Suitable for Paddy-Cum-Fish Culture:
All fishes are not suitable for such a type of culture as paddy-fields provide special ecological conditions such as shallow turbid water with high temperature.
Fishes having the following criteria are generally selected for paddy-cum-fish culture:
(1) Fishes that can adapt to shallow waters necessary for paddy crops.
(2) Fishes that can tolerate high temperature.
(3) Fishes that can thrive on low dissolved oxygen, which is the characteristic of paddy-fields especially in tropical countries.
(4) Fishes that can tolerate fairly high turbidity.
(5) As the duration of culture is quite short, fishes that have high growth rate is to be selected, so that it can reach marketable size within these few months.
(6) Fishes that can live in confinement and do not tend to escape from the cultivated area.
Fishes that are cultured in such waters in India are Mugil sp., Mystus gulio, Haplochromis mellandi (mollusc eating fish), hates calcarifer, Mugil parsia, Puntius sp., Channa sp., prawns and shrimps. In India, limited experimental works have shown the suitability of Indian carps for such integrated farming.
(c) Management of Paddy-Fields:
To increase the utility of paddy-fields as fish ponds, the following managements are required:
(1) A continuous flow of water in the field, with proper inlet and outlet is to be maintained.
(2) The water in the field is to be maintained at a desired level.
(3) Proper drainage of water from the field has to be made in case of flooding.
(4) At the point of entry and exit of water, some control means (such as screens) have to be provided to prevent the cultivated species from escaping and stopping the entry of wild fishes into the paddy-field.
(5) Deep pits or other devices has to be provided as shelter to the cultivated fishes at the time of distress.
(d) Types of Paddy-Field Aquaculture:
Three major types of paddy-field aquaculture are generally practiced:
(i) Simultaneous or combined or synchronous farming.
(ii) Alternate or sequential farming or paddy- fish rotation.
(iii) Relay farming.
(i) Simultaneous or Combined or Synchronous Farms:
In such farming paddy and fish are grown together and harvesting the paddy and fish at the end of the rice-growing season.
Literature reveals that a variety of techniques and stocking rates have been employed in different countries on paddy-field aquaculture. In general, fishes are stocked not earlier than 5 days after transplantation of paddy seedlings, so as to enable the seedlings to form proper root. After transplantation of paddy, stocking in case of fry should be done after 10 days, while for fingerlings after 3 weeks.
The methods of culture adopted are for production of either fingerlings or fish for consumption. Farmers generally cultivate local varieties of paddy which takes up to 6 months to be harvested, so that more than one crop per year can be grown. Generally organic manures are preferred over the use of fertilisers in the preparation of the paddy-fields.
The advantages of simultaneous cultivation are:
(1) There is no additional cost for fish production.
(2) Fishes contribute to the enhancement of paddy production by destroying weeds, causing tillering and mineral enrichment by their digging activity, and for the fertilisation of soil by their excrement and also by the unutilised artificial feed.
(3) Due to fish cultivation paddy production gets increased by 5 to 15%.
The disadvantages are:
(1) The water depth being shallow hinders better fish raising.
(2) For fear of harmful effect on fishes, herbicides and insecticides uses in paddy-field is generally prevented which ultimately limits paddy production.
(3) Due to abrupt changes in temperature and dissolved oxygen, inadequate space and presence of piscivore birds, there is great loss of fishes which may be about 20-60%.
Progressive agricultural areas have slowly discarded paddy-fish cultivation in favour of the rotation of paddy and fish crops.
(ii) Alternate or sequential farming or paddy- fish rotation:
It is the simplest form, where flooded paddy-fields after harvest are used to raise one or more crops of fish or shrimp.
In rotation system the paddy-field has to be prepared for raising fishes after the harvest of rice. To maintain the required depth of water the bunds surrounding the field have to be raised. After harvesting the rice, the stubbles are not removed.
These submerged stubbles provide the substrate for the development of fish food organisms. These stubbles undergo decomposition, thereby fertilising the water and stimulating higher productivity. After fish harvesting, the residues remain in the soil which in turn serves as fertiliser for the paddy crop.
Shrimp Production in Paddy-Fields:
Shrimp production in paddy-fields is generally practised in areas (generally in the west coast and deltaic areas of eastern India) where only one crop (July to September) of a salt-resistant variety of paddy is grown. Following the harvesting of rice, the bundhs are strengthened and sluice gates are installed to control the water supply.
At high tides, the fields are filled with tidal water, containing a large number of shrimp larvae. These larvae gain access to the fields, where they find food and shelter. To attract the larval shrimps, lamps are hung above the inlets.
By this process, natural stocking of shrimp larvae is done at every high tide for two to three months. To prevent the escape of juvenile shrimps at low tides, conical bag-nets are attached to the sluice gates.
Shrimp harvesting from these fields starts in December, as by this time the early stock of shrimps will have attained marketable size. Regular harvesting is done which results in thinning of the stock, leading to better growth rate and harvesting of larger shrimps. The total yield of shrimp is around 780-2100 kg per hectare.
Advantages of Paddy-Fish Rotation:
The paddy- fish rotation system has the following advantages:
(1) There is no water depth limitation either to paddy or fish cultivation. Shallow water depth is maintained till the harvesting of paddy, after which the water depth is raised for the culture of fishes.
(2) Through this adequate water level management, suitable water temperature and dissolved oxygen content can be maintained.
(3) After harvesting of paddy, the submerged stubbles decompose and fertilise the water. This leads to the development of fish food organisms and ultimately stimulates higher productivity.
(4) The interval between paddy harvesting and fish stocking is sufficient enough to allow degradation of pesticides.
(5) Insect pest infestation gets reduced as their life-cycles are disrupted.
(6) Either monoculture or polyculture can be practised.
The disadvantages are:
Due to presence of piscivorous birds like herons, cormorants, etc., considerable loss of fish (20-60%) takes place.
(iii) Relay Farming:
This system is much complicated and it ensures prolonged period of fish culture. It involves transferring the stock of fishes to specially prepared ditches, channels or pools at the time of paddy harvest and re-stocking them in the field for a further growing period. This system provides better growth rate than what is possible in such a short duration of one paddy crop.
For such a cultivation the farm should have additional holding or rearing facilities for the period between paddy harvesting and planting of new fish seedlings. The carps or shrimps can be grown to the required size through adequate feeding. This culture involves higher inputs including labour.
2. Duck-Cum-Fish Farming:
Although duck and fish farming have been in practice in eastern Europe and China and their compatible nature being recognised since long, the interaction and benefits of the association have been understood only a few years back.
During the last decade suitable methods have been developed in various countries for raising ducks in fish ponds. Undoubtedly, such a combined culture is highly profitable as it greatly increases the production of protein in terms of fish and duck per unit area.
The combination of duck and fish farming is seen presently as a means of reducing the cost of feed for ducks, at one hand, and on the other, the excreta of ducks acts in an inexpensive way of fertilising ponds, which results in production of fish food organisms.
Thus, ducks can be said to be ‘living manuring machines’. The duck droppings contain 25 per cent organic and 20 per cent inorgaic substances along with a number of elements such as carbon, nitrogen, phosphorus, potassium, calcium, etc.
Moreover, ducks by agitating the shore areas of the pond, help to release nutrients. Besides this, ducks feed on a variety of organisms such as weeds, snails, unwanted harmful insects and their larvae (some being vectors of fish pathogenic organisms), tadpoles, frogs and water-borne disease-causing organisms infecting man, whose eradication is one of the important aspects of farm management.
(a) Ducks Culture and their Raising:
Ponds provide a clean and healthy environment for ducks. Special strains of ducks have been developed that are suited for pond raising. Such suitable strains when used, approximately 50-60 per cent of their droppings when falls into the pond, is sufficient to fertilise the water.
Reliable and timely supply of required strains of good quality ducklings are of great significance as it promotes successful farming. For supply of ducklings, small scale farmers have to depend on outside sources, while larger farms have their own breeding centres which is much convenient and profitable.
Raising of Ducks is done by one of the two ways:
(i) Extensive Raising:
In extensive raising ducks are stocked at approximately 150-500 per hectare of pond surface. Here small amount of supplementary feed is provided and the number of ducks is limited due to the food they can find in the pond water. As the number of ducks are limited, they contribute little amount of manure to the pond and its effect on fish yield is also limited. Such a type of method is usually employed in Europe.
(ii) Intensive Raising:
Here ducks are stocked at a much higher density, approximately 1000-2500 per hectare of pond surface and is usually employed in Africa. The ducks are fed at the same rates as on land. As ducks are held at a much higher density per unit area, higher amounts of manure are thus loaded into the fish pond which subsequently results in higher yields.
(b) Duck Keeping:
There are two basic ways of keeping ducks in fish ponds:
(i) Free-Range System:
Here the ducks are allowed to have free access to the whole pond (Fig. 6.43). As they are allowed to swim freely around the whole pond surface, a good proportion of their droppings fall directly into the pond water and are distributed more or less uniformly.
The ducks are able to forage around the whole pond. Adjacent to the ponds, small duck houses are built with facilities for providing them with supplementary feed. In this system, as considerable energy is spent by the ducks in swimming activity, it is believed to affect the feed conversion ratio and growth rate of the ducks.
(ii) Confinement in Enclosures:
Here, part of the pond area and the adjacent land area are enclosed with wire fences (Fig. 6.44). About one-fourth of the enclosure will be on the land and the rest in water. Within the wire fence suitable feeding and resting areas are made.
Some of the droppings of the duck falls directly into the pond water, while the rest that drops on land is washed down into the pond. Under this system fish production is reported to be almost equal to the free-range system. Keeping ducks in enclosures is preferred by most farmers, who use special strains of ducks for better growth.
(c) Raising of Fish:
For duck-fish farming the most suitable pond is the barrage type of ponds. This is made by damming shallow valleys, so that the ducks can lie on the natural slopes. There is every likely-hood that ducks may damage the earthen dykes while foraging. The problem can be solved with proper maintenance.
Commonly the fish species cultured are herbivores and omnivores. The common carp was traditionally the main species but subsequently other species of Chinese carps are used to make full use of the food resources. Other important species used are male or hybrid tilapia, grey mullet, catla, eel, asian catfish and sea perch. Fairly high stocking rates are adopted and supplementary food is also provided.
(d) Advantages and Disadvantages of Fish-Cum- Duck Culture:
(1) There is practically less additional cost for fish culture, as the excreta of the ducks fertilises the pond water.
(2) Ducks by agitating the shore areas of the ponds help to release nutrients.
(3) The cost of feed for the ducks gets reduced.
(4) The ducks help to eradicate vectors of fish pathogenic organisms and water borne diseases — causing organisms infecting man, as they feed on a variety of organisms such as weeds, snails, unwanted harmful insects and their larvae, tadpole, frog, etc.
(1) The fingerlings released should be of more than 10 cm size, otherwise the ducks may feed on the fingerlings.
(2) While foraging for food, ducks sometimes damages the earthen dykes. This problem can be solved with proper maintenance.
3. Fish-Cum-Poultry Farmings:
Integrated fish farming with poultry is generally cultured as the poultry manure is a very efficient fertilizer for fish ponds. The poultry droppings comprises 2% nitrogen, 1.25% phosphoric acid and 0.75% potash. The low feeding cost per individual bird makes poultry farming along with fish, a common investment for poor farmers.
(a) Poultry Raising:
Both ‘broilers’ and ‘layers’ variety of chicken can be raised for fish-poultry farming. One day old chick are raised up to the pullet stage after which they are put in layer cages.
Fish culture with both intensive and extensive poultry productions have been integrated successfully. The most intensive type of poultry production is the battery type of housing, which is installed by the side of the pond. The floor of the house is cemented and is set up at a slope so that the eggs may roll forward.
For layers, the floor area required is about 30 cm2 while for broilers, 15-20 cm2. The usual floor space allotted for each bird is 20 x 30 x 40 cm. The birds are confined to cages which are made up of standard, stout, galvanised wire. The cages are kept on trays for collection of droppings. For further on poultry refer chapter 5.
For manuring one hectare pond water, the droppings of about 250 layers and four batches of 200 broilers each are adequate in a year’s time.
(b) Fish Raising:
For fish raising the ponds are stocked with fingerlings of catla, silver carp, common carp, murrels, tilapia, giant freshwater prawns, etc. The stocking density of fishes is related with that of poultry and also with the period of culture.
In one hectare pond area, when stocked with 5000 giant freshwater prawns (Macrobrachium rosenbergii) and 1500 silver carp, and cultured for a period of four months, one can harvest 600 kg of prawns and an equal amount of fish, along with 250 culled birds.
For culturing over a period of one year, ponds may be stocked with fingerlings of catla, common carp, silver carp and grass carp at a density of 5000-6000 fingerlings per hectare. At the end of twelve months of fish-cum-poultry culture, fish yield of over 3900 kg per hectare can be normally obtained along with 42,000 eggs and 200 culled birds.
(c) Advantages and disadvantages of fish-cum- poultry culture:
(1) Chicken manure is a very efficient fertiliser, so no chemical fertiliser is needed for fertilising the pond water. This cuts down the expenditure of rearing fishes.
(2) No supplementary fish feed is required.
(3) The purchase and feeding cost per bird is low.
(4) Chicks are readily available and their productivity can be improved with simple and cheap management.
(1) Chicks should be examined from time to time and diseased one should be isolated, otherwise they will destroy the entire stock.
(2) Sufficient time should be given from one stocking of chicks to the next for renovation of the house and disinfectioning it.
4. Kish-Cum-Pig Culture:
In integrated fish farming with pig, the ‘pig dung’ is useful for conditioning the soil and providing the necessary nutrients required for fertilising the pond water. Fish-cum-pig culture is practised at large in China where pigs are considered as “costless fertiliser factories”.
Pig dung contains about 70 percent digestible feed for fishes. The feed while passing down the pig’s alimentary canal, gets mixed up with enzymes which continue to act even after defecation. Such undigested solids serve as direct food source for tilapia and common carp.
In tropical fish ponds, weeds are a major problem in fish culture. Such vegetation’s are considered as valuable food resource for pigs.
Thus, pigs aptly play a role in biological control of weeds:
(a) Pig Rearing:
In fish-cum-pig culture the embankments of fish ponds are made wider (over 10 m in China) to facilitate the building of pig sites and also for growing vegetables, fruit trees or other crops. In the slopes, grasses can also be grown which is used as fodder for grass carp and for other farm animals.
Various aquatic plants, such as azolla, duck weed, Pistia, Wolffia, Lemna, and water hyacinth (Eichhor-nia) are grown in feeder channels and irrigation ditches associated with the pond farms. These and the foliage of other terrestrial plants (vegetables, rice, corn, etc.) are used for feeding the pigs.
In the water area of the pond, about 10 tons of aquatic plants can be produced, which are sufficient to feed 10 pigs. These plant materials are generally mixed with bananas, coconut meal, rice bran, soybean wastes, groundnut cakes, fish meal, etc.
Pig sites or pen or sty are generally built on nearby land or on the pond embankment. The pen enclosure is built not only for pig raising but also special consideration is given to the needs for breeding, nursing and fattening activities. Pig pen generally have a system of channels for transferring the organic matter into the pond water.
Alternatively, the sty or pen may be constructed above the pond water. The structure is made of wood and provided with a lattice type of floor which permits the excreta and uneaten food to fall directly into the pond water.
Modern practices are to avoid direct washing of the wastes into the pond. The urine and dung of pigs are first allowed to the oxidation tanks (digestion chambers) where sedimentation and fermentation of the manure take place. The supernatant liquid, at regular intervals, are then discharged into the fish ponds.
The sludge that remains is utilised as fertilisers in agriculture. Alternatively the pig manure may be kept in a heap on the pond embankment for later use. The chemical composition of pig wastes is depicted in Table 6.13.
The number of pigs to be raised per hectare and the manuring rates to be applied are based on years of experience. The production of manure depends upon the age and size of the pig. A piglet produces about 3.4 kg manure a day, while a one-year-old pig gives about 12.5 kg a day.
The average production of faeces and urine per pig is about 7.8-8 tons per annum. A density of 60-100 pigs has been found to be sufficient to fertilise a one hectare fish pond.
(b) Fish Rearing:
Polyculture is commonly practised in such integrated farming due to the variety of food that becomes available in the pond. Herbivorous and omnivorous fishes are used for culture; generally common and Chinese carps and less frequently catfishes (Pangasius), Indian carps and tilapia.
Due to high productivity of the ponds, fairly high rates of stocking are generally practised — 60,000 fingerlings of different species (weighing 20-30 gm) per hectare.
(c) Production and Duration of Culture:
The duration of culture of fishes and pigs varies. Generally it is about one year, but culture for 6 months duration is also practised. The overall economics of combined fish and pig rearing depends on the local conditions. However, the pigs are generally sold when they have attained a weight of 90-100 kg. The production of fish generally varies between 2 and 18 tons per hectare per annum.
(d) Advantages and Disadvantages of Fish-Cum- Pig Culture:
(1) Such integrated farming increases the productivity per area and thus, the farmers income becomes doubled or more.
(2) Pig dung conditions the soil of a new pond and provides ready-made organic matter, containing the necessary nutrients.
(3) Pig dung contains about 70 per cent digestible feed for fishes. The undigested solids present in the faeces of pig serves as direct feed source for tilapia and common carp.
(4) Pigs aptly plays a role in biological control of weeds, as weeds are considered as valuable food source for pigs.
(1) Addition of too much pig manure may lead to increased nutrient load resulting in pollution of the water body and mortality of the fishes.
(2) Considerable care and management skills are required to prevent pollution. It has been found that satisfactory fish production can be obtained with much lower manuring.
5. Other Animals in Fish Systems of Integrated Farming:
(a) Fish-Cum-Cattle Farming:
Cattle wastes and washings from the cattle sheds are conveyed through pipes into the ponds which acts as good fertiliser. Cattle wastes are generally collected in a pit for later use. In addition to fish yield, production of milk from cattle and beef adds to the economy.
(b) Fish-Cum-Rabbit Farming:
Rabbit farming has been found to be ideal for integration with small- scale fish culture. Rabbit manure have greater value as a direct food for fish compared to other livestock wastes.
(c) Fish-Cum-Mulberry Farming:
Mulberry plants are raised on the dikes of the fish farm and in the neighbouring fields for silkworm production. The mulberry wastes and silkworm larvae and pupae (after removal of silk) are used as feed for the fishes. It also fertilises the pond water.
Advantages of Integrated Fish Farming:
The advantages of integrated fish farming are as follows:
(1) Full utilisation of farm wastes.
(2) Utilisation of the cooperative effects of interrelated farm activities.
(3) It increases employment opportunities.
(4) It increases nutritional source for the farmer’s family.
(5) It gives higher and stable farm productivity and there is less risk (biologically and economically).
(6) It increases the income of rural population.
(7) It is a means of land reclamation in certain areas.
(8) It is an efficient and economic means of environmental management.
Disadvantages of Integrated Fish Farming:
Recently, controversy has arisen among scientists on the public health aspects of integrated farming. Speculations are ripe that integrated fish farming with pigs and poultry may be a cause of influenza pandemic. This may be, as the pigs would act as ‘mixing vessels’ for avian and human influenza viruses, it can create new lethal strains of viruses by mutation.
In such an act, fishes themselves do not play any role. However, there is no conclusive evidence that integrated farming can become a public health hazard. For safety measures, pig-poultry combinations in integrated fish culture should thus be avoided.