Acclimation to warm temperatures modulates lactate and malate dehydrogenase isozymes in juvenile Horabagrus brachysoma (Günther)

Differential expression of isozymes enables fish to tolerate temperature fluctuations in their environment. The present study explores the modulation of lactate dehydrogenase (LDH) and cytoplasmic malate dehydrogenase (sMDH) isozyme expression in the heart, muscle, brain, liver, gill, and kidney of juvenile Horabagrus brachysoma after 30 days of acclimation at 26, 31, 33, and 36°C. LDH and sMDH zymography were performed using native polyacrylamide gel electrophoresis. The zymography revealed five distinct bands of LDH isoenzymes (labelled from cathode to anode as LDH-A4, LDH-A3B1, LDH-A2B2, LDH-A1B3, and LDH-B4) and three distinct bands of sMDH isoenzymes (labelled from cathode to anode as sMDH-A2, sMDH-AB, and sMDH-B2), with considerable variation in their expression in the tissues. Acclimation to the test temperatures did not influence the expression patterns of LDH or sMDH isozymes. Densitometric analysis of individual isozyme bands revealed a reduction in the densities of bands containing the LDH-B and sMDH-B molecules, while the densities of bands containing the LDH-A and sMDH-A molecules increased in the gills and muscle, indicating the role of these organs in adaptive responses to thermal acclimation. However, the total densities of the LDH and sMDH isozymes increased with higher acclimation temperatures, indicating that adaptation to increased temperatures in H. brachysoma is primarily characterised by quantitative changes in isozyme expression

An overview of enclosure culture in inland open-waters: Responding to socio-economic, ecological, and climate change issues in inland fisheries

Not AvailableIndia has vast and varied inland open-waters which are important culture and capture fisheries resources of the country contributing significantly to the national economy while providing livelihood to millions of countrymen. The inland water areas especially under reservoirs (3.52 million ha), wetlands (0.42 m ha), oxbow lakes (0.12 m ha), derelict water (0.23 m ha) and brackish water (1.16 m ha) are amenable for culture-based fisheries development holding very high potential in enhancing inland fish production. Enclosures (i.e., cages and pens) installed in such open-waters are useful for rearing fingerlings as input for enhancement programmes and table fish production reflecting immense socio-economic implications for poor inland fishers. Floating cage enclosures are most suitable for waterbodies vulnerable to occasional flood. The conventional pen enclosures are installed in marginal areas of floodplain wetlands that can be suitably reinforced to protect the fish crop during flood. Self-recruiting small indigenous fishes can be introduced in pens to provide income and nutritional securities to the fishers. This article reviews enclosure aquaculture technologies in inland open-waters of India with special emphasis on Northeastern region. Socio-economic, ecological and climate-resilience of these technologies are emphasized in this communication, which may encourage higher adoption and consequent increase in fish production from the large inland open-waters of the country

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Not AvailableWorldwide, the practice of culturing fish is becoming increasingly intensified to produce more fish per unit water area available. In India, the Indian major and exotic carps contribute lion’s share in the total aquaculture production, and having good demand as food fish, domestically. Majority of the populace in Northeastern Region of India is fish-eaters, and it has been increasingly felt that they are willing to pay more money to get a local fish (though small) than to buy a large Andhra fish. Consequently, fish farmers are getting interested to culture indigenous fish species opening the avenue for species diversification in the region. Labeo bata, L. gonius, Clarias magur, Heteropneustes fossilis and Monopterus cuchia in Assam, Osteobrama belangeri in Manipur, Notopterus chitala and Ompok bimaculatus in Tripura are in various stages of success while talking of diversification, because breeding, larval rearing and brood stock management are yet to be standardized to the extent it ought to be for many of the fish species mentioned above. Aquaculture is a stressful situation for the cultured fish, more so if the husbandry practices including management of water/ soil qualities and proper feeding are not taken care of. In nature, there exist a delicate balance between the host, pathogen and the environment. Generally high stocking density of fish, insufficient or excess supply of food and poor water quality are the major factors that cause stress to fish favouring the growth and proliferation of pathogens resulting in disease outbreak. The need for adopting suitable health management measures to reduce the loss due to diseases is being increasingly felt by aquaculturists. In disease management, the first and foremost task would be to diagnose and understand the process of disease that is to identify the infectious or non-infectious agent. In general, health management involves preventive and/ or therapeutic strategies. The first strategy includes all measures to prevent the occurrence of diseases and is directed at the environment and host. The latter strategy is on the use of chemicals to target pathogens. One more strategy could be improving immunity of the cultured animals through various means, which might provide protection against various disease causing and non-infectious agents. Under species diversification scenario in aquaculture, as in traditional culture of various species, health management of the animals cultured will be of utmost importance, because pathogens and diseases are causing significant losses in global aquaculture, and therefore the sector is now giving strong emphasis to reducing the mortalities and losses due to diseases. However, it is perceived that species diversification may not aggravate the problem of diseases in aquaculture. Future research could focus on comparative disease resistance capabilities of such indigenous species vis-à-vis traditionally cultured species. Since there is limited information (if any) on disease threats facing indigenous species only, this article will give a brief account of all important pathogenic and non-pathogenic disease conditions in freshwater fish and some newer ideas to deal with diseases in aquatic organisms in general.Not Availabl

Exploring polyculture of small indigenous fshes with major carps in pens as a climate?resilient adaptation strategy for northeastern wetlands of India

Not AvailablePen aquaculture technology, a low-cost aquaculture system for floodplain wetlands of India, was evaluated through a pilot study as an alternative livelihood for increasing adaptive capacity under changing climatic scenario. Five pens (100 m2 area each) were constructed in a floodplain wetland and provisions were made to adjust heights during the monsoon to prevent escapement of fish due to flooding to make it climate-smart adaptation system. Feasibility of culturing high-value locally preferred small indigenous fishes (SIFs), viz. Amblypharyngodon mola, Gudusia chapra and Puntius sophore, along with Indian major carps (IMC) was assessed. Five different species combinations were tested, i.e. P1 (IMC only), P2 (IMC + A. mola @ 30 no./m2), P3 (IMC + G. chapra @ 20 no./m2), P4 (IMC + P. sophore @ 20 no./m2) and P5 (IMC + all three SIFs @ 1/3 of stocking density of each species). The IMC (Labeo catla, L. rohita and Cirrhinus mrigala) were stocked @ 3 no./m2 in all the pens. After 5 months, highest net fish production was obtained from P2 (124.86 kg/pen) followed by P3 (120.19 kg/pen), P5 (105.15 kg/pen), P1 (89.91 kg/pen) and P4 (87.38 kg/pen). The range of water quality parameters recorded during the experimental period was in favourable concentration for fish culture. Economic feasibility analysis of the pen culture operation indicated that culturing IMC with G. chapra or A. mola was more profitable compared to other combinations. The study also showed successful natural recruitment of all the three SIFs in pens indicating that they could breed and continue to support their fishery unlike large carps. With successful culture of fish during flood season, encouraging growth of carps and recruitment of SIFs in pens, it emerged as a potentially effective climate-resilient system which could enhance income and livelihood of the fishers besides providing nutritional security in developing countries

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Not AvailableVulnerability of inland fisheries has been universally and unanimously recognized by fisheries experts all over the world. Before some 20-30 years, experts in the field were probably not bothered about sustainability and vulnerability. The sector at present is facing various man-induced and natural problems which are being assessed either qualitatively or quantitatively employing theoretical and/ or experimental methods. Majority of the man-induced problems are due to increase in the fishers’ population, increased dependency on natural fisheries, increasing fishing efforts, capture of juveniles and brooders from the waterbody etc. Majority of the natural problems are due to abnormal floods, siltation leading to reduced water depths, closure of connecting channels of rivers to the wetlands, abnormal drought-like (dry) situations affecting natural fisheries, etc. The present situation in most of the inland water resources can be termed as highly vulnerable both in the resources and fishers points of view. Research efforts are now directed towards developing/ documenting adaptation strategies so that inland fisheries and fishers dependent on such fisheries can cope with ever-increasing climatic vagaries that are facing the entire system. In this chapter, an account of practical, proven and suggestive technologies or practices is presented as adaptation options in inland fisheries vis-à-vis climate change.Not Availabl

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Not AvailableA 120-day feeding trial was conducted to determine the dietary requirement of phosphorus for Indian major carp, catla (Catla catla) fingerlings. Four hundred and eighty fingerlings (mean body weight: 4.23±0.87?g) were randomly distributed among eight treatment groups with three replicates each. Eight isonitrogenous and isocaloric semi-purified diets (crude protein: 35% and crude lipid: 8.5%) were formulated with graded levels of phosphorus using KH2PO4 (T1: control, 0.1%; T2: 0.3%; T3: 0.5%; T4: 0.7%; T5: 0.9%; T6: 1.1%; T7: 1.3%; T8: 1.5%) and fed to the respective groups. Twenty fish were stocked in 150?L plastic tanks and fed to apparent satiation twice a day. Specific growth rate (SGR) significantly (P<0.05) increased with increasing dietary phosphorus concentration from 0.73% to 1.27%, after which there was a slight decline in growth at 1.1% available phosphorus (aP) and remained constant thereafter. The quadratic broken-line model based on growth was Y=317.5?581(0.64?x) (0.64?x); R2=0.73. Moisture and crude protein contents of whole body were similar among all the treatments. However, the ether extract in T1 group was significantly (P<0.05) higher than all the other treatments. The whole-body phosphorus content increased significantly (P<0.05) with an increase in phosphorus in the diets. The one-slope broken-line model based on whole-body phosphorus concentration was Y=4.07?1.63 (0.71?x); R2=0.48. The one-slope broken-line model for non-faecal phosphorus excretion as inorganic phosphorus (Pi) for 24?h revealed a trend of Y=12.67+73.96 (x?0.6); R2=0.81. Minimum aP requirements based on weight gain (%), whole-body phosphorus content and phosphorus excretion were 0.64%, 0.71% and 0.6%, respectively. Hence, the dietary aP requirement of catla fingerlings ranges from 0.6% to 0.71%.Not Availabl

Acclimation of Anabas testudineus (Bloch) to three test temperatures influences thermal tolerance and oxygen consumption

Teleost fish have developed their own specific adaptive mechanism, both behavioral and physiological, to maintain homeostasis in response to unfavorable temperatures. Therefore, this study was aimed at assessing the critical thermal maxima (CTMax), critical thermal minima (CTMin), and oxygen consumption rate of Anabas testudineus (17.03 +/- A 1.2 g) after acclimating to three preset temperatures (25, 30, and 35A degrees C) for 30 days. The CTMax and CTMin were 40.15, 41.40, 41.88A degrees C and 12.43, 13.06, 13.94A degrees C, respectively, and were significantly different (P < 0.05). The thermal tolerance polygon for the specified temperatures was 278.30A degrees C-2. The oxygen consumption rate (117.03, 125.70, 198.48 mg O-2 kg(-1) h(-1), respectively) increased significantly (P < 0.05) with increasing acclimation temperatures. The overall results indicate that the thermal tolerance and oxygen consumption of A. testudineus are dependent on acclimation

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Not AvailableFeasibility of culturing pengba (Osteobrama belangeri) as a candidate species in polyculture along with other carps in net pen enclosure was studied in Takmu lake, Manipur. A net pen measuring 0.1 ha was constructed using nylon net supported by bamboo poles. The average length and weight of stocked fingerlings (@5 no. m-2) were as follows: pengba (9.4 cm, 10.6 g), Labeo catla (16.1 cm, 39.0 g), Labeo rohita (14.8 cm, 38.6 g), Cirrhinus mrigala (16.2 cm, 41.9 g), Hypophthalmichthys molitrix (14.2 cm, 30.3 g), Ctenopharyngodon idella (22.4 cm, 115.2 g) and Cyprinus carpio (14.8 cm, 55.1 g). Fishes were fed pelleted feed (23.4% crude protein) @ 5% of body weight twice-a-day for 180 days. Highest growth (in terms of weight gain % and specific growth rate) was recorded in pengba followed by C. idella, L. catla, C. mrigala, L. rohita, C. carpio and H. molitrix. The pen aquaculture system was also found to be economically viable with a benefit-cost ratio of 1.37. In conclusion, net pen aquaculture of pengba along with other carps is economically viable and technically feasible in floodplain wetlands of Manipur.ICA