Development of fresh water aquaculture is one of the most important production oriented programmes of the country, being implemented by the state/ union territory. Most of the aquaculture practices are practiced in ponds and takes in Bihar. Several aspects of management practices are being investigated of enhancing the fish productivity of pond which enclose brood stock management nutritional management, health and environmental management. Out of the above stated management environmental management is most essential in which hydrobiological factors are taken into consideration. The hydrological factors in which the parameters of water like temperature, transparency pH, dissolved O2, Co2, total alkalanity, hardness, amount of NP"K, amount of free Ammonia play and important role in augumenting fish production of ponds and takes of Saran division, which is essential for meeting nutritional security and earning of livelihood of fish farmers in the state. This type of work would definitely add a lot of knowledge in fish production partially the edible and valuable IMC and Exotic carps from our fresh water inland fisherie resources particularly of saran division.
The present book consists of seven chapters. The first chapter describes the introduction, different name of ponds of saran division and importance of the present work.
The second chapter describes the microbiological status of the water in which fish culture takes place depends on a wide variety of factors influencing the environment, the most important being the organic matter content (Rheinheimer, 1980; Sugita et al, 1985b; Zmyslowska et al, 2003). Variations in the abundance of heterotrophic bacteria in the water samples of the four treatments were the result of differences in management practices resulting in different organic loads in the pond system. Thus the management regimes receiving organic manures (PM and CD) recorded significantly higher populations of total heterotrophic bacteria (P<0.05), compared to other treatments (Tab. 2.3). The highly productive nature of the manured ponds was also supported by the greater abundance (no.IL) of total plankton, compared to the control treatment (Tab. 2.2).
Lower counts of heterotrophic bacteria in control ponds not receiving any organic manuring have been reported earlier by many authors (Barat & Jana, 1990; .Jana & De, 1990; Bank et a], 2001; Majumdar et al, 2002). As such, the control system appeared to be less productive, indicated from the significantly lower plankton abundance (P<0.05), compared to the manured treatments (Tab. 2.2). According to Ludwig (1999), when organic fertilizers are added to a pond, they are decomposed by bacteria and the water rapidly gains nutrients from the bottom. The released nutrients are rapidly utilized by phytoplankton and other bacteria, which are simultaneously grazed by single cell protozoan and other zooplankton. In control ponds, as also observed in our study, there are few nutrients, and hence few living organisms.
Although heterotrophic bacteria and phytoplankton are important components in the cycle of organic matter and inorganic nutrients in aquatic ecosystems, they may affect each other positively or negatively, depending on the nutrient conditions of their environment (Wang & Priscu, 1994; Kamjunke et al, 1997; Duvall et al, 2001). Because bacteria have a high surface area to volume ratio (Curnie & Kalff, 1984), it has been suggested that bacteria should be superior competitors with phytoplanlcton for nitrogen and phosphorus (Elser et al, 1995). However, in our experiment, higher abundances of heterotrophic bacteria in manured treatments correlated with high phytoplankton abundance (in PM, r=0.625; P<0.01; in CD, r=0.588; P <0.01).
Brett et al., (1999) suggested that the underlying mechanisms behind the positive correlation between phytoplankton and bacteria are tangled in complex interactions between factors such as inorganic nutrient concentrations, organic nutrient availability, protozoan bactivory, availability of physical substrate, as well as light and temperature. Such complications could prevent augmented bacterial populations from having significant effects on phytoplankton. In experiments by Cottingham et al (1997), bacteria did not buffer phytoplankton responses to nutrient enrichment. In view of the continuous grazing pressure on bacteria and phytoplankton by zooplankton and on zooplankton by fish larvae, it is very difficult to estimate the exact population density of bacteria, phytoplankton or zooplankton in any aquatic system. However, the overall results clearly demonstrate the importance of pond management on the growth responses of heterotrophic bacteria.
The abundance of heterotrophic bacteria in the pond sediments did not differ from one system to another (Tab. 2.3). This implies that the sediment in all fish ponds in our experiment, regardless of the farming system, contained the optimal amount of essential nutrients necessary for rapid growth of heterotrophic bacteria. Jana & De (1990) obtained similar results in the sediment of traditional and manure treated ponds. According to Jinyi et al (1988), because of the sedimentation of applied manure and pond mud in both manure-applied and controlled ponds, the amount of bacteria in the water column decreases between the bottom of the pond and the surface layer of water with the continuous release of microorganism from the sediments. Similar results were obtained in our study (Tab. 2.3).
Greater abundance of Aeromonas sp. and Pseudomonas sp. in the water and sediments of Saran district, Gopalganj district and Siwan district, compared to the control treatment, indicate their sewage character. Very high counts of Aeromonas sp. and Pseudomonas sp. in ponds manured with animal excreta have been reported by many authors (Cloete et al, 1984; Jinyi et al, 1987; Jinyi et al, 1988; Hamza et al, 1998) The introduction of live plankton in the LF treatment, however, significantly reduced the population of total heterotrophic bacteria, as well as Aeromonas and Pseudomonas in both water and sediment, compared to the manured treatments (Tab.-2.3).
The water quality was also influenced by the management conditions. Significantly high NH4-N in the PM and CD treatments could be related to the greater abundance of heterotrophic bacteria in these treatments, apart from ammonifying bacteria, which was not enumerated in our experiment, many heterotrophic bacteria are known to utilize nitrogen-rich substrates and release ammonia or ammonium salts (Jana & Barat, 1983). Yao & Zhaoyang (1997) reported that the contact layer between pond mud surface and water is the major source of nutrition. The organic nitrogen decomposed to NH4 - N by bacterial activity adheres to the surface of the mud before being released in the water where it continuously rises to the surface of the water and escapes into the air (Blackburn & Henriksen, 1983; Mei et al, 1995).
Depletion of dissolved oxygen after manure application often leads to heterotrophic organisms in the water utilizing NO3-N as electron receptors instead of oxygen, thus converting it to nitrite (Boyd, 1990). Higher concentration of BOD, NH4 - N, NO2-N and other nutrients, along with the higher counts of Aeromonas sp. and Pseudomonas sp. in the manure treated culture regimes may have lowered the grazing activity by the carp, compared to the LF treatment. Neutral to acidic pH in the water of a majority of the treatments (Tab. 2.1) could be related to the acidic nature of water bodies in North Bengal (Nath et al, 1994; Jha & Barat, 2003; Jha et al, 2003). Lower range of pH values in the PM and CD ponds could be attributed to the animal manure applied in these treatments (Tha et al, 2004; Jha et al, 2006; Jha et al, 2007).
Zooplankton is required as a first food for most cultured fish (Ludwig, 1999). In an earlier experiment, a direct correlation (r=0.957; P<0.05) was observed between the weight gain of koi carp and the amount of zooplankton present in tanks under different doses of organic manuring (Jha et al, 2004). The maximum concentration of zooplankton in the LF treatment could be the consequence of improved water quality, expressed in terms of lower values of BOD, NH4 - N and NO2-N, and higher values of dissolved oxygen, which is conducive to fast reproduction of some of the major zooplankton constituting the main food item of carps (Jana & Chakrabarti, 1993), and also due to the regular introduction of plankton.
Higher weight gain and survival rate of koi carp in the LF treatment could be attributed to better water quality (Tab.-2.1) in that treatment (Jha & Barat, 2005c). Again, the differences in the weight gain of koi carp observed among the different treatments were not essentially due to changes in the water quality, since, weight gain in the C treatment was lower than PM and CD treatments P<0.05), despite having better water quality. It might well be that the weight gain was more directly related to the differences in food concentration, although the zooplankton concentration and water quality were closely related to each other.
All aquaculture production systems must provide a suitable environment to promote the growth of aquatic crops. Although application of organic manure does not directly cause bacterial diseases in fish, the significantly greater abundance of pathogenic bacteria (Aeromonas sp. and Pseudomonas sp.) in the water and sediments of the manured treatments (PM and CD) could lead to diseases. Should fish resistance to disease be low, the possibility of occurrence of bacterial disease is higher in these treatments. Therefore, proper pond management should be observed to prevent any chance of bacterial disease.
Though it has been established that high fish yield in culture systems can be achieved by higher abundance of plankton through organic manuring, practical alternatives to pond manuring are needed because manuring may reduce water quality. Intensive stocking of ornamental fish ponds in India requires a standard water quality to be maintained throughout, so that fish growth is not adversely affected. In view of the financial constraints of marginal farmers who cannot afford modern aeration or waste-treatment equipments, raising of ornamental carp larvae in ponds fed exogenously with zooplankton is of considerable significance because not only would such feeding support high rates of survival and production, it would also maintain greater abundance of zooplankton in the system and better water quality with lower concentrations of Aeromonas sp. and Pseudomonas sp. in the system.
The third chapter describes the concentration of dissolved substances and suspended substances, in natural water is the useful parameters for describing the chemical density and morphology of a given water body has been presented. They also act as a fitness factor and a general measure of productivity. Inter-pond differences of total dissolved solids and planktonic biomass were significant (P < 0.05). The values of total dissolved solids and biomass remained high for the whole study period showing the richness of water in nutrients and production. Electrical conductivity is the measure of electrolytes. Temperature and ecological conditions are responsible for the fluctuations of salt contents which, in turn, influence the production and growth of fish (Jana et at, 1981). Concentration of electrolytes remained quite high for the whole period of research work (Table 3.3). Seasonal fluctuations in electrical conductivity occurred in both the ponds. However, inter-ponds differences for electrical conductivity were non-significant.
Dissolved oxygen is the most significant ecological factor of the fish pond ecosystem. Mahboob (1992) recorded the maximum average dissolved oxygen when there was abundance of phytoplankton. Similar trend was observed in this investigations. The water remained close to the saturation values with regard to oxygen showing the presence of healthy environment for fish in most of the study period.
Total hardness mainly on the cations of Ca+2 and Mg+2 interms of CaCO3 as reported by All and Khan (1976). Inter-pond differences in total hardness was non-significant. High values of hardness might had affect the fish growth.
The concentration of NO3 and ammonia (NH3) remained very high for the whole period both in the ponds which might had affected the fish growth as the concentration of total ammonia was significantly higher than the maximum recommended concentrations in carp ponds (Boyd, 1981).
Therefore it is concluded that the application of organic and inorganic fertilizers, tend to produce changes in ecological conditions through plankton production.
The chapter four describes a study was carried out on the optimal dose of inorganic fertilizer used in carp polyculture system over a period of 10 months. Three treatments were assigned: without inorganic fertilizer, with the application of 100 kg/ha/month inorganic fertilizer and 150 kg/ha/month inorganic fertilizer as T1, T2 and T3, respectively. Each treatment had three replications. The selected indigenous carp species were Rui (Labeo rohita), Catla (Catla catla) and Mrigal (Cirrhinus mrigala), and exotic carp species were silver carp (Hypophthalamichthys molitrix), grass carp (Ctenopharyngodon idella), common carp (Cyprinus carpio) and thai sarpunti (Barbodes gonionotus). The average water area of the experimental ponds was 0.11± 0.01 ha and average depth of water in all ponds was 1.26 m. The treatments showed no effect on water temperature, dissolved oxygen, alkalinity and pH. The fish production was significantly higher (P>0,05) in both the treatments T2 and T3 than that of Ti where no inorganic fertilizer was used. But there was no significant difference between T2 and T3 and T2 was with lower dose inorganic fertilizer (100 kg/ha/month) than T3. Therefore, 100 kg/ha/month inorganic fertilizers may be suggested in carp polyculture system for better production.
The Chapter fifth describes Fish in eutrophic lakes may therefore influence iron metabolism in two widely different ways. First, feces from those fish spending part of their time in the littoral region consuming benthic organisms and sediments make sediment-derived iron available for phytoplankton production in the epilimnion. This may be important, especially during summer stagnation when the supply of iron from tributaries is low. Second, fish mucus may chelate iron, and in the epilimnion with high densities of fish, the chelators in the mucus may increase the selective advantage of organisms with their own chelator-producing capacities, such as the cyanobacteria, so that the presence of large cyprinid populations may contribute to the dominance of cyanobacteria in eutrophic lakes.
The Chapter sixth describes Classical genetic studies provided invaluble information about the genetic traits of organisms until the discovery of recombinant DNA technology. However, the discovery of recombinant DNA technology provided the impetus for scientists to utilize this technology to engineer a specific genetic trait in a directed fashion. The ability to introduce or knock out functional genes using this technology has provided a very powerful tool for scientists to understand biological processes and systems.
The first microinjection method enabling the introduction of a transgene into an organism was reported in 1966, and after a lapse of ‘15 years, the first transgenic mice were produced in the early I 980s. Since the production of the first transgenic mice, gene transfer technology has been pioneered using the mouse model, and the mouse continues to serve as a starting point for gene transfer procedures. However, fish systems have recently started to be accepted as models by many investigators in both applied and basic research, since fish systems possess several attractive attributes, such as genetic mechanisms that correspond to mice and human models, the ease of generating large numbers of animals in a short period compared to other vertebrate model organisms, and the ability to make genetic crosses among phenotypically diverse fish.
The complete sequencing of a human genome propelled science into a postgenome era. In this postgenome era, fish, as the most diverse vertebrate systems, represent a better candidate for promoting comparative genomics than any other system. It is clear that comparative genomic studies using different model organisms will facilitate the understanding of many important phenomena, such as physiological mechanisms. Transgenic fish generated by introducing or knocking out a functional gene of interest will be unique tools in unraveling the complex phenomena playing a major role in physiological processes. Therefore, new initiatives by a large number of investigators are currently focusing on the use of transgenic fish in biomedical research. For instance, researchers from a Canadian biotechnology company reported the use of transgenic tilapia carrying a human insulin gene for the transplantation of insulin- producing islets to humans. Since fish are further away from humans on the evolutionary scale, if transgenic fish are used as bioreactors, cross transfer of disease is much less likely.
Gene transfer into fish was accomplished in the early 1990s. However, since then many initiatives have been undertaken to achieve the goal of generating superior fish strains with improved growth rates, increased disease resistance, higher food conversion efficency, and many other desirable charcteristics. The research results reported in recent years from a number of laboratories and private companies have demonstrated that the production of transgenic fish strains with improved growth rates, cold resistance and increased disease resistance can be achieved using this technology.
The applications of transgenic fish technology in aquaculture and biomedical research can provide a considerable number of benefits. However, it needs to be acknowledged that there are currently several major problems that need to be solved in order to utilize this technology efficently and safely. These problems include the absence of a convenient procedure for the mass identification of transgenic fish, random integration of a transgene that may potentially interrupt a functional gene in the host, and horizontal contamination or toxic effects of the transgene on other organisms in the ecosystem. These problems can be solved by developing rapid and convenient procedures for the identification of transgenic fish, developing methods for targeting transgene integration sites in fish genome and assessing safety and the environmental impact of transgenic fish.
The Chapter seventh describes the whole summary and conclusion of the present research work.
