Brood Fish Transport

In India two successful models of closed system live fish carrier tanks have been designed to carry brood fishes. One is due to Mammen (1962b), which is known as “splash less tank”. The latest model of the “splash less tank” is of petrol tanker design of 150l capacity with an auto clave type lid. It has a built in aeration system for supplying compressed air, which works on a belt driven by the engine of the transporting vehicle. An oxygen cylinder is carried only as a stand by emergency. The inside of the tank is lined by U-foam which prevents the physical injury to live fish during transport. A total weight of 250kg brood fish can be transported at a time in “splash less tank” Adult Catla weighing about 60kg has been transported in this tank successfully. Generally one kg fish is transported with 4.5l of water.

The other live fish carrier is designed in India by Patro (1968). Patro’s carrier is of a laboratory gas supply design type and comprising an outer chamber of 120cm dia open from top and slightly smaller inner one closed from top, the later during transport, fits inside the former. The inner chamber is provided with an air vent and an oxygen valve. The outer chamber serves as a storage tank and initially filled with water along with fishes to be transported. The U-foam prevents the fishes from injury during transport. The double barrel sized carrier described by Patro, can transport 100kg of brood fish at a time. The oxygen is supplied in the tank with an interval of 5hrs to keep the fish healthy.

Some chemicals are also used to transportation of live brood fish. The sedatives are used in transportation can decrease the rate of oxygen consumption and reduce the rate of excretion of carbon dioxide, ammonia, and other toxic wastes. It can control the excitability of the fish, thus reducing the chances of injury.

Natural Resources of Seeds:

In early days generally seeds of Indian Major Carps are collected from natural resources for culture in fish farms. The techniques of collection of seeds from natural resources are described bellow.

Site Selection for Collecting Fish Seeds:

Before selecting a suitable site for collection of spawn in a given stretch of river, a pre monsoon survey is generally conducted. The river meandering with oxbow lakes, flooded areas of river banks, shallow areas flooded with rain water are suitable for collection of fish seeds. The bends and curves of various shapes in the river course often show a precipitous, fast eroding bank on one side, called here, ‘erosion zone’ and a flat, gently slopping bank exactly opposite, called ‘shadow zone’. Both these banks are unsuitable for collection of spawns. Better collection sites lie on the side of the slopping bank, but at spot where the current just diverges casting off spawns to the sides, as if by centrifugal force. At such sites, a large number of spawn collection nets are usually be operated.

Gears Used for Collection of Spawns:

The spawns are collected by special type of nets, called shooting nets. This is a funnel shaped, net of finely woven netting and is operated in shallow margins of flooded rivers with mouth of the net facing the current. At the end of the net a bag like structure is attached, called ‘gamcha’ to store the spawn inside of it. After a certain periods of time, the cod the spawns are collected at this cod end. The net is fixed by four bamboo poles, against the current of rivers. Various types and modification of these nets are used in different parts of India. In North-east Bengal, the spawn collection nets are called benchi jal. In South-western part, the nets are called Midnapur type nets.

Methods of Collection:

The shooting nets are fixed in such a way that its axis is in line with current directions. To start with bamboo pole is planted firmly in the selected spot, the loops of one end of the nets mouth slipped over it, the other end is stretched firmly across the path of the current and fixed in place with the help of another bamboo pole. The net is then allowed to drift in the current, mouth facing to the current of water. The net is then stretched firmly along the axis, by pulling the cod end ring which is then fixed in place with the help of more bamboo poles. The anterior end of ‘gamcha’ is then tied round the ring, while the posterior end is fixed in position with the help of two more bamboo poles. In order to prolong the life of the net and ‘gamcha’, they should be invariably pulled out of the water after 12hrs operation and dried for at least 24hrs.

After storing suitable quantity of fish seeds, the tail pieces of nets are removed and the spawns or seeds of fishes are scooped out. The collection of seeds from tail pieces are carried on after an interval of 15min, 30min, 1hrs, or 2 hrs depending on the intensity of the collections. Before scooping, the debris accumulated inside the ‘gamcha’ are removed carefully with expertise hands.

Methods of Measuring the Quantity of Spawns:

The spawn collected is to be measured in 200ml, 100ml, 50ml, 30ml, 20ml, 10ml or 5ml measuring cups, depending upon their bulk. For temporary storage the spawns are stored in hapas, made up with muslin cloth, fixed in the shallow water of river margins or creeks.

Site Selection for Aquaculture

Introduction

The success of an aquaculture enterprise is dependent on many factors including the selection of a suitable site and the design and construction of facilities that enable efficient and economic operation. This information briefly discusses the major factors that must be considered when selecting a site and designing grow out facility for the aquaculture of finfish; most factors also apply to crustaceans. Success or failure of any aquaculture venture largely depends on the right selection of the site for it. In choosing a site several factors other than the physical aspect of the site are to be considered.

Sites suited for aquaculture and culture types

Several types of water bodies can be used for fish culture - the choice of a specific body would depend on the objective of the investors and also the type of aquaculture.

Among the sites suitable for aquaculture could be listed: land-swamps, rivers, stream beds; coastal areas - bays, estuaries backwaters, lagoons, salt marshes and mangrove swamps; lakes, reservoirs and other water bodies, including irrigation tanks and canals.

The specific site to be chosen would be based on the requirement of the culture systems. Static water ponds are the most common, hence pond culture the most important system. Most of these are confined to freshwater areas, but brackish water ponds are also becoming more common. There is a variety of culture systems which can be developed in open waters - the stocking and management of open waters themselves being major occupation, e.g. extensive stocking of man-made reservoirs and lakes. In the larger freshwater bodies and coastal areas cage and pen culture can be developed. Site selection for these culture systems has to be carefully done, based on the requirements of the species to be cultured and the structures to be erected for the culture. Here and in the culture systems where closed systems are used, the inputs required can be costly and management intensive. Thus there can be gradation of culture, systems based on the input costs and management strategy employed, from extensive, through semi-intensive to intensive.

Culture types (Systems)

The different culture systems in vogue are listed below:

Static water ponds, running water culture, culture in recirculation systems (closed or reconditioned water); culture in rice fields and integrated culture systems, as the duck-cum-fish and pig-cum-fish culture - or any fish-livestock-crop combination; culture in raceways, cages, pens and enclosures; also mollusk/oyster culture - hanging, on-bottom and stick methods. As mentioned already the choice of site for a specific culture system, would depend on the characteristics of the site and the requirement of the culture system - the latter again has two components, the species requirements and the structural requirements of the culture system.

Various Factor Affecting the Site Selection of Aquaculture:

1. Socioeconomic and Political factor:
They are socio-economic aspects such as
Social and religious customs’
Consumer preference;
Nature of manpower (labor) - quality and quantity - available;
Transportation and communication facilities; i.e. infrastructure facilities;
Accessibility and nearness to market;
Availability of construction materials

2. Political and Legal Consideration:

The aquaculture project execution should be a part of the overall planning for the specific area under the national plan for development, so that the project can fit into the country's or provincial plan for development of industry and agriculture. This is specially needed when aquaculture is a part of rural development programme, as indeed most such projects are. This should specially help in sharing infrastructural facilities of transportation (road), power supply and communications and also in judicious sharing of imports and recycling outputs. The advantages of their consideration in sitting a project are obvious. We shall look into these aspects of macro-economic planning subsequently when “socio-economic aspects” and “aquaculture planning” are discussed in detail. Legal aspects, such as security of tenure, maritime laws controlling coastal waters (in cases where sites are coastal), legal size limits with reference to the ponds/culture area, as well as the species under culture, and closed reasons, should also to be considered. Several countries already have certain regulations concerning these legal aspects, some of which are in force, much before aquaculture was thought of as an industry.
In many cases these legal clauses cannot be easily modified, even though some attempt in this direction would be necessary, especially with reference to size-limits of fish and closed seasons. The latter regulations have been included to protect the species' survival under intensive capture systems of wild stock. While this protection may be necessary for such a case, here in aquaculture, and capture from the wild fish of certain size, when the season for capture is closed legally, is only for protection of the fish by way of transferring the fish to culture ponds - either as brood fish or as fry or fingerlings in grow-out ponds. In some cases maritime areas through which navigational routes and certain other country priorities exist. These aspects should be considered in choosing the site for the aquaculture ventures planned.
3. Major Climatic and Environmental factor:

Climatic factor: Fishes and crustaceans are poikilotherms (cold-blooded animals) and temperature directly affects all aspects of their biology. Each species has a range of temperatures in which it can live. Temperatures reaching the upper or lower lethal limits will kill the animals. If animals are subjected to extreme but not lethal temperatures for extended periods, growth and other biological activities will be adversely affected and mortalities will occur; either directly through malfunction of one or more physiological processes or indirectly (for example, through stress-induced disease and starvation). Within the tolerance range, each species has a range of temperatures, which enable maximum growth (the optimum temperature range). At temperatures outside this range, feeding rates and the efficiency of food conversion are generally poorer, resulting in slower growth and lower production. Locate aquaculture facilities in an area that has the optimum temperature regime for the selected species. Regions where lethal temperatures are reached, or approached, are unsuitable for pond culture.

Other Environmental Factors:

a) Topography and Ground Elevation: Large commercial fish farms are typically built on flat land. Pond bottoms drop approximately 0.2 foot for every 100 feet of length, a slope of 0.2%. Topography with slopes of 0-2% is better for pond construction. Extensive earth moving may be required on land with slopes greater than these; increasing construction costs. Some innovative farmers use terracing -- stair-stepping -- for pond layouts in hollows or on land with slopes greater than 2%. However, the economics of that method should be carefully examined. It is important that ponds have an adequate drainage area for harvest. The site should be above the 25-year flood plain.
b) Soil: the site must have soils that hold water and can be compacted. If pond levees are constructed with soil that has high water permeability (leakage), the cost of pumping water could become prohibitive. Soils should contain no less than 20% clay. Soils with high sand and silt compositions may erode easily and present a piping hazard -- soil-water flow along pipes -- which could wash out a levee. Anti-seep collars can help minimize that problem. Clay oil with greater than 40% clay is suitable for pond and pond dyke construction. Silt clay (40-60% clay), sandy clay (35-55% clay), Clay loam (27-40% clay) are also suitable for aquaculture site.
c) Water Supply, Water Quality: Aquaculture requires large volumes of good quality water. While you may be able to fill a pond with your garden hose, it may take six months to do so. Normally, a well or surface water source (river, stream or spring) is required. Surface sources may be polluted, intermittently available (affected by weather, e.g. drought) or contain wild fish populations which might be introduced into your pond. Wild fish can be a source of disease and will often compete with cultured fish for feed. Many of the most successful aquaculture operations in the U.S. depend on large aquifers (underground water supplies) for water needs. Typically, commercial aquaculture requires a water flow rate of 25-40 gallons/minute, on demand, for every surface acre (4 acre-feet) of pond water. Water must be of high quality and free of pollutants, sewage and toxic contaminants. Generally, water that is safe for livestock and domestic use or that supports wild fish populations is safe for aquaculture. However, livestock and aquaculture do not mix. Manure from just a few farm animals can pollute a pond. There are several chemical characteristics of water that are desirable for good fish growth. Water should have a pH of 6.5-9.0, total alkalinity of 75-250 mg/l and total hardness of 75-250 mg/l. Total hardness and alkalinity should not be less than 20 mg/l. Low alkalinity and acid water are usually related to acid soils. Agricultural limestone can be used to raise pH, alkalinity and hardness to the minimum required levels in soft, acid water. If striped bass or red drums are being considered, calcium hardness and total alkalinity between 100-250 mg/l are preferable; a calcium hardness value of 250 mg/l is ideal. Often, well water contains no oxygen and high levels of carbon dioxide and nitrogen, necessitating aeration before use or pH testing.
d) Productivity: The soil must be productive and fertile enough to produce require micro and macro vegetation of the pond and planktonic growth.
e) Other Factors:
· Susceptibility of the site to flooding
· Non availability of migratory birds, predators
· Previous land use and surrounding land use
· Environmental Consideration: Aquaculture is an Environmentally Relevant Activity and will require an Environmental Authority or approval from the Environmental Protection Agency (EPA) to authorize activities
· Wind drift and Arial application

Methods of Liquid Waste Treatment

Sewage Treatment

A high BOD indicates the presence of excess amounts of organic carbon. Oxygen depletion is a consequence of adding wastes with high BOD values to aquatic ecosystems. The higher the BOD of a source of wastes the higher the polluting power of that waste. BOD's of certain wastes are listed in the table below.

Type of Waste BOD(mg/L)
Domestic Sewage 200-600
Slaughterhouse Wastes 1000-4000
Cattle Shed Effluents 20000
Vegetable Processing 200-5000

There are numerous ways to reduce the BOD of waste before discharging it into the water. Treatment of the wastes is aimed at removing organic material, human pathogens, and toxic chemicals.

Primary sewage treatment involves physical separation to lower the BOD of the waste. Suspended solids are removed in this step through the use of settling tanks. Primary treatment usually removes from 30% to 40% of the BOD from typical domestic sewage. Secondary treatment uses microbial degradation to reduce the concentration of organic compounds further; it involves microbial processes which can be aerobic or anaerobic. The combined use of primary and secondary treatment reduces approximately 80% to 90% of the BOD. However, because secondary treatment involves micro organisms it is extremely sensitive to toxic chemicals. Finally, tertiary treatment uses chemicals to remove inorganic compounds and pathogens.

Oxidation Ponds

Oxidation Ponds are also known as stabilization ponds or lagoons. They are used for simple secondary treatment of sewage effluents. Within an oxidation pond heterotrophic bacteria degrade organic matter in the sewage which results in production of cellular material and minerals. The production of these supports the growth of algae in the oxidation pond. Growth of algal populations allows furthur decomposition of the organic matter by producing oxygen. The production of this oxygen replenishes the oxygen used by the heterotrophic bacteria. Typically oxidation ponds need to be less than 10 feet deep in order to support the algal growth. In addition, the use of oxidation ponds is largely restricted to warmer climate regions because they are strongly influenced by seasonal temperature changes. Oxidation ponds also tend to fill, due to the settling of the bacterial and algal cells formed during the decomposition of the sewage. Overall, oxidation ponds tend to be inefficient and require large holding capacities and long retention times. The degradation is relatively slow and the effluents containing the oxidized products need to be periodically removed from the ponds. An oxidation pond can be seen in the figure below.

Trickling Filter

The trickling filter system is relatively simple and inexpensive. It is an aerobic sewage treatment method in which the sewage is distributed by a revolving sprinkler suspended over a bed of porous material as seen in the Figure below.

The sewage slowly moves through the porous bed and the effluent is collected at the bottom. This porous material becomes coated with a dense slimy bacterial growth which provides a home for a heterogeneous microbial community which includes bacteria, fungi, and protozoa as well as other organisms. As the sewage drains through the porous bed, this microbial community absorbs and breaks down dissolved organic nutrients in the sewage; this reduces the BOD. Aeration of the sewage occurs by the movement of air through the porous bed. The sewage may need to be recirculated several times through the filter in order to reduce the BOD sufficiently. One dissadvantage to this system is that an excess amount of nutrients produces an excessive amount of slime on the bed which in turn reduces aeration, leading to the need to renew the porous bed. Cold winter temperatures also reduce the effectiveness of this method in outdoor treatment facilities.

Activated Sludge

Activated Sludge is a widely used aerobic method of sewage treatment. After primary settling, the waste stream is brought to an aeration tank. Air is put in and/or there is mechanical stirring which provides aeration of the waste. Sludge from a previous run is usually reintroduced to the tanks to provide microorganisms. This is why it is called activated sludge. During the period in the aeration tank, large developments of heterotrophic organisms occur. In the activated sludge tank the bacteria occur in free suspension and as aggregates or flocs. Extensive microbial metabolism of organic compunds in the sewage results in the production of new microbial biomass. Most of this biomass becomes associated with flocs that can be removed from suspension by settling. A portion of the settled sewage sludge is recycled and the remainder must be treated by composting or anaerobic digestion. Combined with primary settling, activated sludge reduces the BOD by 85% to 90%. It also drastically reduces the number of intestinal pathogens. An illustration of an aeration basin is shown below.

Anaerobic Digestors

Anaerobic digestors are large fermentation tanks which are continuously operated under anaerobic conditions, as seen below.

Anaerobic decomposition could be used for direct treatment of sewage, but it is economically favorable to treat the waste aerobically. Large-scale anaerobic digestors are usually used for processing of the sludge produced by primary and secondary treatments. It is also used for the treatment of industrial effluents which have very high BOD levels. The mechanisms for mechanical mixing, heating, gas collection, sludge addition and removal of stabilized sludge are incorporated into the design of large-scale anaerobic digestors. Anaerobic digestion uses a large variety of nonmethanogenic, obligately, or facultatively anaerobic bacteria. In the first part of the process, complex organic materials are broken down and in the next step, methane is generated. The final products of anaerobic digestion are approximately 70% methane and 30% carbon dioxide, microbial biomass and a nonbiodegradable residue.

Tertiary Treatment

The treatment processes used to reduce the BOD of sewage waste are secondary treatment processes. Tertiary treatment is any practice beyond secondary treatment and is designed to remove nonbiodegradable organic pollutants and mineral nutrients such as nitrogen and phosphorus salts. For tertiary treatment, activated carbon filters are commonly used.

Disinfection

Disinfection is the final step in the sewage treatment process and is designed to kill enteropathogenic bacteria and viruses that were not eliminated during the previous stages of treatment. Disinfection is commonly done by chlorination with chlorine gas or hypochlorite. Chlorine gas reacts with water to yield hypochlorous and hydrochloric acids which are the actual disinfectants. A disadvantage of using chlorination for disinfection is the formation of disinfection by-products, such as chlorinated hydrocarbons. Chlorinated hydrocarbons are toxic and difficult to mineralize. Trihalomethanes may also be formed such as chloroform and bromoform, which are suspected carcinogens. Ozonation is an alternative to chlorination, which uses ozone as the oxidant. This however, is more expensive. Currently, alternative disinfection processes are being sought.

Inbreeding

In fish farming, if proper care is not taken the fishes can breed with their close relatives or same parental generation which may cause early mortality of fish, poor growth rates and other genetical abnormalities. This phenomenon is called inbreeding or homozygosis and the offspring is called homozygote. Homozygosis is the condition when two genes at particular locus are with same allele. Inbreeding causes the reduction of desirable traits and some times may cause fertility. If a farm based on limited number of population of brood stocks the progeny over long periods can face inbreeding problems.

The advantage of inbreeding:

Sometime the inbreeding is not encouraged and has some advantageous point also. Production of inbreed lines are very use full in improvement of stock. Production of inbreed lines have following advantages.

· To produce pure lines of fish
· Pure lines of strains are used for perfect hybridization of fish to obtain favourable heterosis, monosex.
· Pure lines help in gene mapping
· To determine

1. Phenotypical variations
2. Extent of inbreeding depression
3. chromosomal makeup to the fish

Integrated Fish Farming

Integrated fish farming is the methods by which fish is cultured along with paddy, piggery, poultry or any livestock, or flower culture.

Fish farming along with paddy culture:

In certain areas, paddy fields are flooded with water for at least 3-8months in a year. During which the fishes or prawns can be cultured along with the paddy fields to increase the annual income of a farmer. Fish culture in paddy fields can be categorised by following ways –

1. The water is allowed to enter into the paddy fields during cultivation with some wild verities. The paddy fields are surrounded to prevent the escape. No special attention is taken for that. This is a type extensive culture.
2. The paddy fields can be used as temporary ponds after harvesting of paddy. In this method fish and paddy is not cultured together. Fish seeds of suitable species are stocked with minimum care.
3. A continuous fish culture is done in specially prepared ditches or canals when fields are drained.

Advantages:

· The excretory matter of fish is used as manure for paddy cultivation
· Insects which can harm paddy crops are eaten by the fishes
· Fish destroy the unwanted weeds and increased the production of paddy.

Generally in WB, Rohu, Catla, Mrigal and all air breathing fishes are cultured along with paddy. Fresh water prawns, Tilapia and other cyprinids are also cultured.

Fish farming along with Duckery or Poultry:

Fish can be cultured along with livestock. The system is advantageous because duck feeds miscellaneous items from water like insects, crustaceans, molluscs which are not economical. The duck droplling is used as foods as well as fertilisers of ponds. The dabbling of duck in pond water in search of feeds release the nutrients from soil as well as it mixes the oxygen to the water which enhances the biological productivity and consequent increase of fish growth. The duck does not need any elaborate house and most of the time they prefer to live in water. Improve stocks of ducks like – India Runners, are used in poly culture system. 200 – 300 ducks are culture along with fish which can make sufficient amount of fertiliser to the pond water. The culture can yield from one ha area – 3,500-4000kg of fish, 18,000 eggs and 500kg of duck meat in one year.

Fish cum Pig Farming:

Fish farming with pig rearing is also cost effective and extra source of income to the fish farmers. Four types of pigs are used in that case in India of which Hampshire and Land Race are mostly cultured. They are prolific breeders and attain slaughter house maturity (60-70kg) with in 6 months and give 6-8 piglets. Fish attains marketable size in a year during which two crops of pigs can be reared. Pig manure is also rich with all nutrients found in cow dung. Fully grown pigs can void 500-600kg manure in a year. 30 – 40 pigs are sufficient to one ha farm for adequate fertilisation.

The yield is about from poly culture system –

6000 – 7000kg fish/ha/yr with 3,600 – 5000kg of pig meat

Cross Breeding

Crossbreeding is the solution of inbreeding depression, because the fishes are allowed to breed with different breed verities, strains or genotypes of farmed species. To improve the stocks artificial selection techniques are applied. This is called selective breeding. From heterozygosis the stocks can be improved and the aims of cross breeding to achieve –
· Better growth rate
· Better desired qualities
· Better FCR value
· Increase the survival rate and lowered the early stage of mortality

Gynogenesis

It is the process to produce individuals from maternal chromosomes only eventually to obtain homozygosity. Gynogenesis in fish farming is used to form inbred lines to achieve proper hybridization and selective breeding.

Methods:

Sperm nucleus is inactivated prior to fertilization by use of X-Rays, chemicals – dimethyl sulphate.
Upon fertilisation the resulting diploid individuals retain the second polar body nucleus (maternal) besides the egg nucleus, because the eggs are exposed to sub lethal temperature shocks before or after fertilization which suppress the meiotic divisions of eggs i.e. ensuring the non reduction of nuclear components.

In India Gynogenesis are tried on Indigenous as well as Exotic carps. Eggs of rohu are fertilised with irradiated sperms of Catla and then exposed to cold 12°C and heat 39°C shocks to obtain gynogenetic rohu.